Use standard random library

Addresses compiler warnings and use of deprecated functions.

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));

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);

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));
 

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);

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) {

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:

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));
         }
       }

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);

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);

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);

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);
     }
   }
@@ -36,17 +36,17 @@ 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++;
   //         }
   //     }
   // }
   //
   // 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));
   // }
 }

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,

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:

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);

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: