From e8a38a5f03cdac6b5ae6cebd6d2b9d42499fd609 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bjarki=20=C3=81g=C3=BAst=20Gu=C3=B0mundsson?=
 <bjarki.agust@gmail.com>
Date: Mon, 30 Dec 2024 13:57:47 +0000
Subject: [PATCH] Use standard random library

Addresses compiler warnings and use of deprecated functions.
---
 code/data-structures/avl_tree.test.cpp      | 12 ++++++------
 code/data-structures/kd_tree.test.cpp       |  8 ++++----
 code/data-structures/misof_tree.test.cpp    |  8 ++++----
 code/data-structures/sparse_table.test.cpp  |  2 +-
 code/geometry/welzl.cpp                     |  2 +-
 code/graph/bipartite_matching.test.cpp      |  4 ++--
 code/graph/bipartite_mvc.test.cpp           |  8 ++++----
 code/graph/blossom.cpp                      |  2 +-
 code/graph/dinic.test.cpp                   |  6 +++---
 code/graph/edmonds_karps.test.cpp           |  6 +++---
 code/graph/gomory_hu_tree.test.cpp          | 10 +++++-----
 code/graph/hld.test.cpp                     |  7 -------
 code/graph/hopcroft_karp.test.cpp           | 10 +++++-----
 code/graph/tarjan_olca.test.cpp             | 14 +++++++-------
 code/header.cpp                             |  3 +++
 code/mathematics/berlekamp_massey.test.cpp  | 20 ++++++++++----------
 code/mathematics/fastmul.test.cpp           | 10 ++++------
 code/mathematics/fft.test.cpp               |  8 ++++----
 code/mathematics/fht.test.cpp               |  6 +++---
 code/mathematics/intx.test.cpp              |  4 ++--
 code/mathematics/linear_recurrence.test.cpp | 14 +++++++-------
 code/mathematics/miller_rabin.cpp           |  2 +-
 code/mathematics/miller_rabin.test.cpp      |  2 +-
 code/mathematics/mod_inv_sieve.test.cpp     |  2 +-
 code/mathematics/tridiagonal.test.cpp       |  2 +-
 code/other/dpll.test.cpp                    |  8 ++++----
 code/other/lis.test.cpp                     |  2 +-
 code/other/simulated_annealing.cpp          |  3 +--
 code/other/stable_marriage.test.cpp         |  6 +++---
 code/strings/aho_corasick.test.cpp          |  8 ++++----
 code/strings/kmp.test.cpp                   |  8 ++++----
 code/strings/suffix_array.test.cpp          |  4 ++--
 code/tricks/is_square.test.cpp              |  2 +-
 tester/test_footer.cpp                      |  1 -
 tester/test_header.cpp                      |  4 ++--
 35 files changed, 105 insertions(+), 113 deletions(-)

diff --git a/code/data-structures/avl_tree.test.cpp b/code/data-structures/avl_tree.test.cpp
index c125023..e5b7831 100644
--- a/code/data-structures/avl_tree.test.cpp
+++ b/code/data-structures/avl_tree.test.cpp
@@ -10,18 +10,18 @@ void test() {
   assert_equal(0, t1.size());
 
   for (int i = 0; i < cnt; i++) {
-    int n = rand() % range;
+    int n = rng() % range;
     avl_tree<int>::node *p = t1.insert(n);
     assert_equal(n, p->item);
     t2.insert(n);
     assert_equal((int)size(t2), (int)size(t1));
 
-    int n1 = rand() % range;
+    int n1 = rng() % range;
     avl_tree<int>::node *b = t1.find(n1);
     if (b) assert_equal(n1, b->item);
     assert_equal(b == NULL, t2.find(n1) == t2.end());
 
-    int n2 = rand() % range;
+    int n2 = rng() % range;
     t1.erase(n2);
     t2.erase(n2);
     assert_equal((int)size(t2), (int)size(t1));
@@ -33,18 +33,18 @@ void test() {
   assert_equal(0, t1.size());
 
   for (int i = 0; i < cnt; i++) {
-    int n = rand() % range;
+    int n = rng() % range;
     avl_tree<int>::node *p = t1.insert(n);
     assert_equal(n, p->item);
     t2.insert(n);
     assert_equal((int)size(t2), (int)size(t1));
 
-    int n1 = rand() % range;
+    int n1 = rng() % range;
     avl_tree<int>::node *b = t1.find(n1);
     if (b) assert_equal(n1, b->item);
     assert_equal(b == NULL, t2.find(n1) == t2.end());
 
-    int n2 = rand() % range;
+    int n2 = rng() % range;
     t1.erase(n2);
     t2.erase(n2);
     assert_equal((int)size(t2), (int)size(t1));
diff --git a/code/data-structures/kd_tree.test.cpp b/code/data-structures/kd_tree.test.cpp
index b596e94..d00a457 100644
--- a/code/data-structures/kd_tree.test.cpp
+++ b/code/data-structures/kd_tree.test.cpp
@@ -66,7 +66,7 @@ void randomize_pt() {
       hi = 10;
 
   for (int i = 0; i < CURK; i++) {
-    pt[i] = static_cast<double>(rand()) / RAND_MAX * (hi - lo) + lo;
+    pt[i] = uniform_real_distribution(lo, hi)(rng);
     pt[i] = round(pt[i] * 3.0) / 3.0;
   }
 }
@@ -80,7 +80,7 @@ void test() {
   for (int t = 0; t < 100; t++) {
     // printf("%d\n", t);
 
-    int startcnt = rand() % 1000;
+    int startcnt = rng() % 1000;
 
     vector<kd_tree<CURK>::pt> pts1(startcnt);
     vector<naive_kd_tree<CURK>::point> pts2(startcnt);
@@ -112,7 +112,7 @@ void test() {
     int ops = 1000;
     int found = 0;
     for (int cop = 0; cop < ops; cop++) {
-      int op = rand() % 3;
+      int op = rng() % 3;
 
       if (op == 0) {
         // insert
@@ -147,7 +147,7 @@ void test() {
       } else if (op == 2) {
         // nearest neighbour
         randomize_pt();
-        bool allow_same = rand() % 2 == 0;
+        bool allow_same = rng() % 2 == 0;
         // bool allow_same = true;
 #if TREE1
         pair<kd_tree<CURK>::pt, bool> a = tree1.nearest_neighbour(kd_tree<CURK>::pt(pt), allow_same);
diff --git a/code/data-structures/misof_tree.test.cpp b/code/data-structures/misof_tree.test.cpp
index 3b7e78b..3000682 100644
--- a/code/data-structures/misof_tree.test.cpp
+++ b/code/data-structures/misof_tree.test.cpp
@@ -5,10 +5,10 @@ void test() {
   avl_tree<int> t2;
 
   for (int i = 0; i < 1000000; i++) {
-    int op = rand() % 3;
+    int op = rng() % 3;
 
     if (op == 0) {
-      int x = rand() % (1 << BITS);
+      int x = rng() % (1 << BITS);
 
       // printf("insert %d\n", x);
 
@@ -20,14 +20,14 @@ void test() {
       else i--;
 
     } else if (op == 1 && size(t2) > 0) {
-      int x = t2.nth(rand() % size(t2))->item;
+      int x = t2.nth(rng() % size(t2))->item;
 
       // printf("erase %d\n", x);
 
       t1.erase(x);
       t2.erase(x);
     } else if (op == 2 && size(t2) > 0) {
-      int n = rand() % size(t2);
+      int n = rng() % size(t2);
 
       // printf("nth %d: %d, %d\n", n, t2.nth(n)->item, t1.nth(n));
 
diff --git a/code/data-structures/sparse_table.test.cpp b/code/data-structures/sparse_table.test.cpp
index 9b27975..fd42e18 100644
--- a/code/data-structures/sparse_table.test.cpp
+++ b/code/data-structures/sparse_table.test.cpp
@@ -14,7 +14,7 @@ struct sparse_table_slow {
 void test() {
     rep(n,0,257) {
         vi arr(n);
-        rep(i,0,n) arr[i] = rand() % 1000000000;
+        rep(i,0,n) arr[i] = rng() % 1000000000;
 
         sparse_table_slow A(arr);
         sparse_table B(arr);
diff --git a/code/geometry/welzl.cpp b/code/geometry/welzl.cpp
index 5feab81..72ee533 100644
--- a/code/geometry/welzl.cpp
+++ b/code/geometry/welzl.cpp
@@ -13,7 +13,7 @@ pair<point,double> welzl() {
           mx = d, res = (wR[i] + wR[j]) / 2.0;
       return make_pair(res, mx/2.0); }
     return circumcircle(wR[0], wR[1], wR[2]); }
-  swap(wP[rand() % wP.size()], wP.back());
+  swap(wP[rng() % wP.size()], wP.back());
   point res = wP.back(); wP.pop_back();
   pair<point,double> D = welzl();
   if (abs(res - D.first) > D.second + EPS) {
diff --git a/code/graph/bipartite_matching.test.cpp b/code/graph/bipartite_matching.test.cpp
index 30f5338..00f5002 100644
--- a/code/graph/bipartite_matching.test.cpp
+++ b/code/graph/bipartite_matching.test.cpp
@@ -17,7 +17,7 @@ void test_rand(int N, int M) {
   for(int i = 0; i < N; i++) {
     g.add_edge(SOURCE, i, 1, 0);
     for(int j = 0; j < M; j++) {
-      if(rand() % 2) {
+      if(rng() % 2) {
         // cout << i << " -> " << j << endl;
         g.add_edge(i, N + j, 1, 0);
         adj[i].push_back(j);
@@ -89,7 +89,7 @@ void test() {
   test_1();
   int TESTS = 1000, MAX_N = 50, MAX_M = 50;
   for(int i = 0; i < TESTS; ++i) {
-    test_rand(rand() % MAX_N, rand() % MAX_M);
+    test_rand(rng() % MAX_N, rng() % MAX_M);
   }
 }
 // vim: cc=60 ts=2 sts=2 sw=2:
diff --git a/code/graph/bipartite_mvc.test.cpp b/code/graph/bipartite_mvc.test.cpp
index 4713bb9..9f8efea 100644
--- a/code/graph/bipartite_mvc.test.cpp
+++ b/code/graph/bipartite_mvc.test.cpp
@@ -1,13 +1,13 @@
 /* Field testing: Kattis sensor */
 void test() {
   rep(ite,0,10000) {
-    int n = rand() % 400 + 1,
-      m = rand() % 400 + 1;
-    int k = rand() % n + 1;
+    int n = rng() % 400 + 1,
+      m = rng() % 400 + 1;
+    int k = rng() % n + 1;
     vii es;
     rep(i,0,n) {
       rep(j,0,m) {
-        if (rand() % k == 0) {
+        if (rng() % k == 0) {
           es.push_back(ii(i,j));
         }
       }
diff --git a/code/graph/blossom.cpp b/code/graph/blossom.cpp
index 25f3d91..5e12d48 100644
--- a/code/graph/blossom.cpp
+++ b/code/graph/blossom.cpp
@@ -73,7 +73,7 @@ vi find_augmenting_path(const vector<vi> &adj,const vi &m){
 vii max_matching(const vector<vi> &adj) {
   vi m(size(adj), -1), ap; vii res, es;
   rep(i,0,size(adj)) iter(it,adj[i]) es.emplace_back(i,*it);
-  random_shuffle(es.begin(), es.end());
+  shuffle(es.begin(), es.end(), rng);
   iter(it,es) if (m[it->first] == -1 && m[it->second] == -1)
     m[it->first] = it->second, m[it->second] = it->first;
   do { ap = find_augmenting_path(adj, m);
diff --git a/code/graph/dinic.test.cpp b/code/graph/dinic.test.cpp
index d2b9ce8..b17b185 100644
--- a/code/graph/dinic.test.cpp
+++ b/code/graph/dinic.test.cpp
@@ -11,7 +11,7 @@ void test1() {
 
   for(int i = 0; i < N; i++) {
     for(int j = 0; j < N; j++) {
-      int cap = rand() % MAX + 1;
+      int cap = rng() % MAX + 1;
       mf.add_edge(i, j, cap);
       mf2.add_edge(i, j, cap);
     }
@@ -34,7 +34,7 @@ void test2() {
 
   for(int i = 0; i < N; i++) {
     for(int j = 0; j < N; j++) {
-      int cap = rand() % MAX + 1;
+      int cap = rng() % MAX + 1;
       mf.add_edge(i, j, cap, cap);
       mf2.add_edge(i, j, cap, cap);
     }
@@ -57,7 +57,7 @@ void test3() {
 
   for(int i = 0; i < N; i++) {
     for(int j = 0; j < N; j++) {
-      int cap = rand() % MAX + 1;
+      int cap = rng() % MAX + 1;
       mf.add_edge(i, j, cap, cap);
       mf.add_edge(i, j, cap, cap);
       mf2.add_edge(i, j, cap, cap);
diff --git a/code/graph/edmonds_karps.test.cpp b/code/graph/edmonds_karps.test.cpp
index 2146060..a5acc16 100644
--- a/code/graph/edmonds_karps.test.cpp
+++ b/code/graph/edmonds_karps.test.cpp
@@ -11,7 +11,7 @@ void test1() {
 
   for(int i = 0; i < N; i++) {
     for(int j = 0; j < N; j++) {
-      int cap = rand() % MAX + 1;
+      int cap = rng() % MAX + 1;
       mf.add_edge(i, j, cap);
       mf2.add_edge(i, j, cap);
     }
@@ -34,7 +34,7 @@ void test2() {
 
   for(int i = 0; i < N; i++) {
     for(int j = 0; j < N; j++) {
-      int cap = rand() % MAX + 1;
+      int cap = rng() % MAX + 1;
       mf.add_edge(i, j, cap, cap);
       mf2.add_edge(i, j, cap, cap);
     }
@@ -57,7 +57,7 @@ void test3() {
 
   for(int i = 0; i < N; i++) {
     for(int j = 0; j < N; j++) {
-      int cap = rand() % MAX + 1;
+      int cap = rng() % MAX + 1;
       mf.add_edge(i, j, cap, cap);
       mf.add_edge(i, j, cap, cap);
       mf2.add_edge(i, j, cap, cap);
diff --git a/code/graph/gomory_hu_tree.test.cpp b/code/graph/gomory_hu_tree.test.cpp
index fad4df0..5db7943 100644
--- a/code/graph/gomory_hu_tree.test.cpp
+++ b/code/graph/gomory_hu_tree.test.cpp
@@ -16,7 +16,7 @@ void test() {
         }
       }
 
-      int cap = rand() % MAX;
+      int cap = rng() % MAX;
       g.add_edge(i, j, cap, cap);
     }
   }
@@ -36,8 +36,8 @@ void test() {
   // int cnt = 0;
   // rep(i,0,N) {
   //     rep(j,0,N) {
-  //         if (rand() % 1000 == 0) {
-  //             g.add_edge(i,j,rand() % MAX);
+  //         if (rng() % 1000 == 0) {
+  //             g.add_edge(i,j,rng() % MAX);
   //             cnt++;
   //         }
   //     }
@@ -45,8 +45,8 @@ void test() {
   //
   // gh = construct_gh_tree(g);
   // rep(i,0,N) {
-  //     int a = rand() % N,
-  //         b = rand() % N;
+  //     int a = rng() % N,
+  //         b = rng() % N;
   //     assert_equal(g.max_flow(a,b), compute_max_flow(a,b,gh));
   // }
 }
diff --git a/code/graph/hld.test.cpp b/code/graph/hld.test.cpp
index 7695f6d..8ae629b 100644
--- a/code/graph/hld.test.cpp
+++ b/code/graph/hld.test.cpp
@@ -75,16 +75,9 @@ struct HLD_naive {
   }
 };
 
-// int randint(int a, int b)
-// {
-//     return rand() % (b - a + 1) + a;
-// }
-
 void test() {
   /* Field testing: SPOJ LCA, SPOJ QTREE, TOJ 2241, Live Archive 2045, Live Archive 6140, UVa 10938, IPSC 2009 L */
 
-  // srand(100);
-
   int ts = 100,
     maxn = 1000,
     maxq = 1000,
diff --git a/code/graph/hopcroft_karp.test.cpp b/code/graph/hopcroft_karp.test.cpp
index 3ba47c8..c2a382c 100644
--- a/code/graph/hopcroft_karp.test.cpp
+++ b/code/graph/hopcroft_karp.test.cpp
@@ -13,7 +13,7 @@ void test_rand(int N, int M, int sparseness = 2) {
 
   for(int i = 0; i < N; i++) {
     for(int j = 0; j < M; j++) {
-      if(rand() % sparseness == 0) {
+      if(rng() % sparseness == 0) {
         g.add_edge(i, j);
         adj[i].push_back(j);
       }
@@ -36,7 +36,7 @@ void test_rand(int N, int M, int sparseness = 2) {
 void test() {
   int TESTS = 1000, MAX_N = 400, MAX_M = 300;
   for(int i = 0; i < TESTS; ++i) {
-    test_rand(rand() % MAX_N, rand() % MAX_M, rand() % 100 + 1);
+    test_rand(rng() % MAX_N, rng() % MAX_M, rng() % 100 + 1);
   }
 }
 
@@ -47,7 +47,7 @@ void test() {
 //
 //     for(int i = 0; i < N; i++) {
 //         for(int j = 0; j < M; j++) {
-//             if(rand() % sparse == 0) {
+//             if(rng() % sparse == 0) {
 //                 cnt++;
 //                 g.add_edge(i, j);
 //             }
@@ -60,8 +60,8 @@ void test() {
 // void test() {
 //     int TESTS = 20, MAX_N = 5000, MAX_M = 5000;
 //     for(int i = 0; i < TESTS; ++i) {
-//         // test_rand(rand() % MAX_N, rand() % MAX_M);
-//         test_rand(MAX_N, MAX_M, rand() % 100000);
+//         // test_rand(rng() % MAX_N, rng() % MAX_M);
+//         test_rand(MAX_N, MAX_M, rng() % 100000);
 //     }
 // }
 // vim: cc=60 ts=2 sts=2 sw=2:
diff --git a/code/graph/tarjan_olca.test.cpp b/code/graph/tarjan_olca.test.cpp
index 2c101dc..0c02fb6 100644
--- a/code/graph/tarjan_olca.test.cpp
+++ b/code/graph/tarjan_olca.test.cpp
@@ -41,8 +41,8 @@ pair<vi*, int> random_tree(int n) {
   union_find uf(n);
 
   for (int i = 0; uf.size(0) < n; i++) {
-    int a = rand() % n,
-      b = rand() % n;
+    int a = rng() % n,
+      b = rng() % n;
 
     if (uf.find(a) != uf.find(b)) {
       uf.unite(a, b);
@@ -51,7 +51,7 @@ pair<vi*, int> random_tree(int n) {
     }
   }
 
-  int root = rand() % n;
+  int root = rng() % n;
   stack<int> S;
   S.push(root);
   bool *visited = new bool[n];
@@ -133,8 +133,8 @@ void test() {
   int tests = 100;
 
   for (int t = 0; t < tests; t++) {
-    int n = rand() % 10000 + 1;
-    int q = rand() % 10000 + 1;
+    int n = rng() % 10000 + 1;
+    int q = rng() % 10000 + 1;
 
     pair<vi*, int> xadj = random_tree(n);
     vi *adj = xadj.first;
@@ -147,8 +147,8 @@ void test() {
 
     vii qs;
     for (int i = 0; i < q; i++) {
-      int a = rand() % n,
-        b = rand() % n;
+      int a = rng() % n,
+        b = rng() % n;
 
       qs.push_back(ii(a, b));
       lca.query(a, b);
diff --git a/code/header.cpp b/code/header.cpp
index 1963cc6..df03a12 100644
--- a/code/header.cpp
+++ b/code/header.cpp
@@ -16,4 +16,7 @@ typedef vector<vi> vvi;
 typedef vector<vii> vvii;
 template <class T> T smod(T a, T b) {
   return (a % b + b) % b; }
+
+default_random_engine rng(
+    chrono::system_clock::now().time_since_epoch().count());
 // vim: cc=60 ts=2 sts=2 sw=2:
diff --git a/code/mathematics/berlekamp_massey.test.cpp b/code/mathematics/berlekamp_massey.test.cpp
index 440ead8..5a59b0c 100644
--- a/code/mathematics/berlekamp_massey.test.cpp
+++ b/code/mathematics/berlekamp_massey.test.cpp
@@ -31,15 +31,15 @@ ostream& operator <<(ostream &outs, const Mod &x) {
 
 void testMod() {
     for (int it = 0; it < 10000; it++) {
-        int K = rand() % 20 + 1,
-            S = rand() % 1000 + 1;
+        int K = rng() % 20 + 1,
+            S = rng() % 1000 + 1;
 
-        int k = rand() % K + 1;
+        int k = rng() % K + 1;
         vector<Mod> init(k);
-        rep(i,0,k) init[i] = rand() % (2*S) - S;
+        rep(i,0,k) init[i] = (int)(rng() % (2*S)) - S;
 
         vector<Mod> c(k);
-        rep(i,0,k) c[i] = rand() % (2*S) - S;
+        rep(i,0,k) c[i] = (int)(rng() % (2*S)) - S;
         rep(i,0,k) {
             Mod cur = 0;
             rep(j,0,k) {
@@ -62,15 +62,15 @@ void testMod() {
 
 void testDouble() {
     for (int it = 0; it < 10000; it++) {
-        int K = rand() % 5 + 1,
-            S = rand() % 10 + 1;
+        int K = rng() % 5 + 1,
+            S = rng() % 10 + 1;
 
-        int k = rand() % K + 1;
+        int k = rng() % K + 1;
         vector<long double> init(k);
-        rep(i,0,k) init[i] = rand() % (2*S) - S;
+        rep(i,0,k) init[i] = (int)(rng() % (2*S)) - S;
 
         vector<long double> c(k);
-        rep(i,0,k) c[i] = rand() % (2*S) - S;
+        rep(i,0,k) c[i] = (int)(rng() % (2*S)) - S;
         rep(i,0,k) {
             long double cur = 0;
             rep(j,0,k) {
diff --git a/code/mathematics/fastmul.test.cpp b/code/mathematics/fastmul.test.cpp
index 5ac2d4b..ad01571 100644
--- a/code/mathematics/fastmul.test.cpp
+++ b/code/mathematics/fastmul.test.cpp
@@ -1,9 +1,9 @@
 
 intx randint(int len) {
   stringstream ss;
-  ss << rand() % 9 + 1;
+  ss << rng() % 9 + 1;
   for (int i = 0; i < len-1; i++)
-    ss << rand() % 10;
+    ss << rng() % 10;
 
   return intx(ss.str());
 }
@@ -11,8 +11,6 @@ intx randint(int len) {
 void test() {
   /* Field testing: SPOJ {MUL,TMUL,VFMUL} */
 
-  srand(1337); // TODO: remove this
-
   int ts = 1000,
     l1 = 1,
     l2 = 1000;
@@ -20,8 +18,8 @@ void test() {
   for (int t = 0; t < ts; t++) {
     // printf("%d\n", t);
 
-    int la = rand() % (l2 - l1 + 1) + l1,
-      lb = rand() % (l2 - l1 + 1) + l1;
+    int la = uniform_int_distribution(l1, l2)(rng),
+      lb = uniform_int_distribution(l1, l2)(rng);
 
     intx a = randint(la),
        b = randint(lb),
diff --git a/code/mathematics/fft.test.cpp b/code/mathematics/fft.test.cpp
index 6c45d41..7b5e20b 100644
--- a/code/mathematics/fft.test.cpp
+++ b/code/mathematics/fft.test.cpp
@@ -86,9 +86,9 @@ intx fastmul(intx an, intx bn)
 intx randint(int len)
 {
   stringstream ss;
-  ss << rand() % 9 + 1;
+  ss << rng() % 9 + 1;
   for (int i = 0; i < len-1; i++)
-    ss << rand() % 10;
+    ss << rng() % 10;
 
   return intx(ss.str());
 }
@@ -102,8 +102,8 @@ void test() {
 
   for (int t = 0; t < ts; t++)
   {
-    int la = rand() % (l2 - l1 + 1) + l1,
-      lb = rand() % (l2 - l1 + 1) + l1;
+    int la = uniform_int_distribution(l1, l2)(rng),
+      lb = uniform_int_distribution(l1, l2)(rng);
 
     intx a = randint(la),
        b = randint(lb),
diff --git a/code/mathematics/fht.test.cpp b/code/mathematics/fht.test.cpp
index fab77a3..a111b60 100644
--- a/code/mathematics/fht.test.cpp
+++ b/code/mathematics/fht.test.cpp
@@ -12,12 +12,12 @@ vi slow(vi a, vi b) {
 
 void test() {
     rep(it,0,1000) {
-        int k = rand() % 10;
+        int k = rng() % 10;
         int n = 1<<k;
         vi a(n), b(n);
         rep(i,0,n) {
-            a[i] = rand() % 200 - 100;
-            b[i] = rand() % 200 - 100;
+            a[i] = uniform_int_distribution(-100, 100)(rng);
+            b[i] = uniform_int_distribution(-100, 100)(rng);
         }
         vi ans = slow(a,b);
 
diff --git a/code/mathematics/intx.test.cpp b/code/mathematics/intx.test.cpp
index 41fb0a1..06565c0 100644
--- a/code/mathematics/intx.test.cpp
+++ b/code/mathematics/intx.test.cpp
@@ -40,13 +40,13 @@ intx gcd(intx a, intx b) {
 //         printf("%d\n", i);
 //         stringstream ss;
 //         for (int j = 0; j < len; j++)
-//             ss << (rand() % 10 + '0');
+//             ss << (rng() % 10 + '0');
 // 
 //         intx a(ss.str());
 //         ss.str("");
 // 
 //         for (int j = 0; j < len; j++)
-//             ss << (rand() % 10 + '0');
+//             ss << (rng() % 10 + '0');
 // 
 //         intx b(ss.str());
 // 
diff --git a/code/mathematics/linear_recurrence.test.cpp b/code/mathematics/linear_recurrence.test.cpp
index 535ea23..84572ab 100644
--- a/code/mathematics/linear_recurrence.test.cpp
+++ b/code/mathematics/linear_recurrence.test.cpp
@@ -15,21 +15,21 @@ void test() {
 
     ll mod = 1000000007;
     for (int it = 0; it < 1000; it++) {
-        int k = rand() % 10 + 1;
+        int k = rng() % 10 + 1;
         vector<ll> init, c;
-        rep(i,0,k) init.push_back(rand() % mod);
-        rep(i,0,k) c.push_back(rand() % mod);
+        rep(i,0,k) init.push_back(rng() % mod);
+        rep(i,0,k) c.push_back(rng() % mod);
         for (int jt = 0; jt < 20; jt++) {
-            ll n = rand() % 10;
+            ll n = rng() % 10;
             assert_equal(slow(init, c, n, mod), nth_term(init, c, n, mod), true);
 
-            n = rand() % 100;
+            n = rng() % 100;
             assert_equal(slow(init, c, n, mod), nth_term(init, c, n, mod), true);
 
-            n = rand() % 1000;
+            n = rng() % 1000;
             assert_equal(slow(init, c, n, mod), nth_term(init, c, n, mod), true);
 
-            n = rand() % 1000;
+            n = rng() % 1000;
             assert_equal(slow(init, c, n, 123456), nth_term(init, c, n, 123456), true);
         }
     }
diff --git a/code/mathematics/miller_rabin.cpp b/code/mathematics/miller_rabin.cpp
index f0959f4..6f3801d 100644
--- a/code/mathematics/miller_rabin.cpp
+++ b/code/mathematics/miller_rabin.cpp
@@ -5,7 +5,7 @@ bool is_probable_prime(ll n, int k) {
   int s = 0; ll d = n - 1;
   while (~d & 1) d >>= 1, s++;
   while (k--) {
-    ll a = (n - 3) * rand() / RAND_MAX + 2;
+    ll a = uniform_int_distribution(2LL, n-1)(rng);
     ll x = mod_pow(a, d, n);
     if (x == 1 || x == n - 1) continue;
     bool ok = false;
diff --git a/code/mathematics/miller_rabin.test.cpp b/code/mathematics/miller_rabin.test.cpp
index 540df41..16d49d4 100644
--- a/code/mathematics/miller_rabin.test.cpp
+++ b/code/mathematics/miller_rabin.test.cpp
@@ -9,7 +9,7 @@ void test() {
   }
 
   for (int i = 0; i < 10000; i++) {
-    int x = rand() % 100000000;
+    int x = rng() % 100000000;
     bool a = is_probable_prime(x, 10),
        b = is_prime(x);
 
diff --git a/code/mathematics/mod_inv_sieve.test.cpp b/code/mathematics/mod_inv_sieve.test.cpp
index a5b0912..5f17a27 100644
--- a/code/mathematics/mod_inv_sieve.test.cpp
+++ b/code/mathematics/mod_inv_sieve.test.cpp
@@ -1,7 +1,7 @@
 #include "../code/mathematics/is_prime.cpp"
 void test() {
   rep(it,0,300) {
-    int p = rand() % 2000000000;
+    int p = rng() % 2000000000;
     while (!is_prime(p)) p++;
     int n = min(100000, p);
     vi inv = inv_sieve(n, p);
diff --git a/code/mathematics/tridiagonal.test.cpp b/code/mathematics/tridiagonal.test.cpp
index f2c7b0c..ebb9ea0 100644
--- a/code/mathematics/tridiagonal.test.cpp
+++ b/code/mathematics/tridiagonal.test.cpp
@@ -2,7 +2,7 @@
 void test() {
   long double eps = 1e-5;
   rep(it,0,5000) {
-    int n = rand() % min(it+1, 4999) + 1;
+    int n = rng() % min(it+1, 4999) + 1;
     vector<long double> cX(n);
     rep(i,0,n) {
       A[i] = randdouble(-1000, 1000);
diff --git a/code/other/dpll.test.cpp b/code/other/dpll.test.cpp
index d7e1fd7..fee847f 100644
--- a/code/other/dpll.test.cpp
+++ b/code/other/dpll.test.cpp
@@ -2,14 +2,14 @@ void test() {
     // Field testing: https://icpc.kattis.com/problems/checks
     // Was too slow on https://open.kattis.com/problems/boardcovering
     rep(its,0,1000) {
-        int n = rand() % 20 + 1,
-            m = rand() % (4*n);
+        int n = rng() % 20 + 1,
+            m = rng() % (4*n);
         vector<vi> cl;
         rep(i,0,m) {
             vi cur;
             while (cur.empty()) rep(j,0,n) {
-                if (rand() % 4 == 0) {
-                    if (rand() % 2 == 0) {
+                if (rng() % 4 == 0) {
+                    if (rng() % 2 == 0) {
                         cur.push_back(-(j+1));
                     } else {
                         cur.push_back(j+1);
diff --git a/code/other/lis.test.cpp b/code/other/lis.test.cpp
index de38395..bd6d220 100644
--- a/code/other/lis.test.cpp
+++ b/code/other/lis.test.cpp
@@ -15,7 +15,7 @@ int lis_dp(const vi &arr, int last) {
 
 void check(int n) {
   vi arr(n);
-  rep(i,0,n) arr[i] = rand() % 100;
+  rep(i,0,n) arr[i] = rng() % 100;
 
   mem.clear();
   int mx = 0;
diff --git a/code/other/simulated_annealing.cpp b/code/other/simulated_annealing.cpp
index 1f16347..f24d2ad 100644
--- a/code/other/simulated_annealing.cpp
+++ b/code/other/simulated_annealing.cpp
@@ -1,13 +1,12 @@
 double curtime() {
   return static_cast<double>(clock()) / CLOCKS_PER_SEC; }
 int simulated_annealing(int n, double seconds) {
-  default_random_engine rng;
   uniform_real_distribution<double> randfloat(0.0, 1.0);
   uniform_int_distribution<int> randint(0, n - 2);
   // random initial solution
   vi sol(n);
   rep(i,0,n) sol[i] = i + 1;
-  random_shuffle(sol.begin(), sol.end());
+  shuffle(sol.begin(), sol.end(), rng);
   // initialize score
   int score = 0;
   rep(i,1,n) score += abs(sol[i] - sol[i-1]);
diff --git a/code/other/stable_marriage.test.cpp b/code/other/stable_marriage.test.cpp
index 9672843..dcb2e21 100644
--- a/code/other/stable_marriage.test.cpp
+++ b/code/other/stable_marriage.test.cpp
@@ -19,15 +19,15 @@ void test() {
 
   for (int t = 0; t < ts; t++) {
 
-    int n = rand() % maxn;
+    int n = rng() % maxn;
 
     for (int i = 0; i < n; i++) {
       for (int j = 0; j < n; j++) {
         m[i][j] = w[i][j] = j;
       }
 
-      random_shuffle(m[i], m[i] + n);
-      random_shuffle(w[i], w[i] + n);
+      shuffle(m[i], m[i] + n, rng);
+      shuffle(w[i], w[i] + n, rng);
 
       for (int j = 0; j < n; j++) {
         minv[i][m[i][j]] = j;
diff --git a/code/strings/aho_corasick.test.cpp b/code/strings/aho_corasick.test.cpp
index 026bb1a..8bd3eac 100644
--- a/code/strings/aho_corasick.test.cpp
+++ b/code/strings/aho_corasick.test.cpp
@@ -31,7 +31,7 @@ struct aho_corasick_slow {
 string random_string(int n, int cc) {
   stringstream ss;
   for (int i = 0; i < n; i++) {
-    ss << static_cast<char>(rand() % cc + 'a');
+    ss << static_cast<char>(rng() % cc + 'a');
   }
 
   return ss.str();
@@ -44,18 +44,18 @@ void test() {
     ts2 = 10;
 
   for (int t = 0; t < ts; t++) {
-    int n = rand() % 1000;
+    int n = rng() % 1000;
 
     vector<string> kws;
     for (int i = 0; i < n; i++) {
-      kws.push_back(random_string(rand() % 10 + 1, rand() % 5 + 1));
+      kws.push_back(random_string(rng() % 10 + 1, rng() % 5 + 1));
     }
 
     aho_corasick ac(kws);
     aho_corasick_slow ac2(kws);
 
     for (int p = 0; p < ts2; p++) {
-      string s = random_string(rand() % 100, rand() % 5 + 1);
+      string s = random_string(rng() % 100, rng() % 5 + 1);
       vector<string> res = ac.search(s);
       vector<string> res2 = ac2.search(s);
       sort(res.begin(), res.end());
diff --git a/code/strings/kmp.test.cpp b/code/strings/kmp.test.cpp
index 246e3d3..5472027 100644
--- a/code/strings/kmp.test.cpp
+++ b/code/strings/kmp.test.cpp
@@ -1,11 +1,11 @@
 string rand_string(int l, int h) {
-  int len = rand() % (h - l + 1) + l;
+  int len = uniform_int_distribution(l, h)(rng);
   stringstream ss;
   rep(i,0,len) {
-    if (rand() % 2 == 0) {
-      ss << static_cast<char>(rand() % 26 + 'a');
+    if (rng() % 2 == 0) {
+      ss << static_cast<char>(rng() % 26 + 'a');
     } else {
-      ss << static_cast<char>(rand() % 26 + 'A');
+      ss << static_cast<char>(rng() % 26 + 'A');
     }
   }
   return ss.str();
diff --git a/code/strings/suffix_array.test.cpp b/code/strings/suffix_array.test.cpp
index a24fecd..9952b57 100644
--- a/code/strings/suffix_array.test.cpp
+++ b/code/strings/suffix_array.test.cpp
@@ -88,10 +88,10 @@ void test() {
   make_sure_ok("ABAAAAAAA");
 
   for (int i = 0; i < 10000; i++) {
-    int len = rand() % 1000;
+    int len = rng() % 1000;
     stringstream ss;
     for (int j = 0; j < len; j++) {
-      ss << static_cast<char>('A' + (rand() % 26));
+      ss << static_cast<char>('A' + (rng() % 26));
     }
 
     string s = ss.str();
diff --git a/code/tricks/is_square.test.cpp b/code/tricks/is_square.test.cpp
index ceb0a3b..2964397 100644
--- a/code/tricks/is_square.test.cpp
+++ b/code/tricks/is_square.test.cpp
@@ -8,7 +8,7 @@ void test() {
   assert_true(is_square(4));
 
   rep(i,0,100000) {
-    int n = rand() % 100000000;
+    int n = rng() % 100000000;
     int st = sqrt(n);
     while (st*st > n) st--;
     while (st*st < n) st++;
diff --git a/tester/test_footer.cpp b/tester/test_footer.cpp
index 65dcb61..3fc6117 100644
--- a/tester/test_footer.cpp
+++ b/tester/test_footer.cpp
@@ -1,5 +1,4 @@
 int main() {
-    srand(time(NULL));
     test();
     assert(!ANY_FAILED);
     return 0;
diff --git a/tester/test_header.cpp b/tester/test_header.cpp
index 93cb435..6e4d7ca 100644
--- a/tester/test_header.cpp
+++ b/tester/test_header.cpp
@@ -48,9 +48,9 @@ void assert_almost_equal(double a, double b, double eps = 1e-9, bool kill = fals
 }
 
 double randdouble(double a, double b) {
-    return static_cast<double>(rand()) / RAND_MAX * (b - a) + a;
+    return uniform_real_distribution(a, b)(rng);
 }
 
 int randint(int a, int b) {
-    return static_cast<int>(randdouble(a, b) + 0.5);
+    return uniform_int_distribution(a, b)(rng);
 }