Update Merge Sort Tree & Create HLD

hld.cpp

@@ -0,0 +1,51 @@
+constexpr int MAXN = 111111;
+
+vector<int> graph[MAXN];
+int par[MAXN], sub[MAXN], dep[MAXN];
+void dfs(int now, int before) {
+    par[now] = before;
+    sub[now] = 1;
+    for(int nxt: graph[now]) if (nxt != before)
+        {
+            dep[nxt] = dep[now] + 1;
+            dfs(nxt, now);
+            sub[now] += sub[nxt];
+        }
+}
+vector<int> chain[MAXN];
+int wt_chain[MAXN], in_chain[MAXN], ps[MAXN], occ = 0;
+void hld(int now, int before, int cur_chain) {
+    wt_chain[now] = cur_chain;
+    in_chain[now] = chain[cur_chain].size();
+    chain[cur_chain].push_back(now);
+    int hvy = -1;
+    for (int nxt: graph[now]) if (nxt != before)
+        {
+            if (hvy==-1 || sub[nxt] > sub[hvy]) hvy = nxt;
+        }
+    if (hvy != -1) hld(hvy, now,  cur_chain);
+    for (int nxt: graph[now]) if (nxt != before)
+        {
+            if (nxt != hvy) hld(nxt, now, nxt);
+        }
+    if (cur_chain == now)
+    {
+        ps[cur_chain] = occ;
+        occ += chain[cur_chain].size();
+    }
+}
+//위치 공식 : ps[wt_chain[a]]+in_chain[a]
+int get_lca(int a, int b)
+{
+    while(wt_chain[a] != wt_chain[b])
+    {
+        if (dep[wt_chain[a]] > dep[wt_chain[b]])
+            a = par[wt_chain[a]];
+        else
+            b = par[wt_chain[b]];
+    }
+    if (in_chain[a] > in_chain[b])
+        return b;
+    else
+        return a;
+}

merge_sort_tree.cpp

@@ -1,83 +1,70 @@
-struct merge_sort_tree
-{
+#define all(v) (v).begin(),(v).end()
+struct merge_sort_tree{
     vector<vector<int>> tree;
     vector<int> a;
     int n;
     int base;
-    merge_sort_tree(int n): n(n)
-    {
+    merge_sort_tree(int n): n(n) {
         base = 1;
         while(base < n) base <<= 1;
         tree.resize(base*2 - 1);
         --base;
         a.resize(n);
     }
-    void init()
-    {
-        for (int i = base; i<base+n;++i)
-        {
+    void init() {
+        for (int i = base; i<base+n;++i) {
             tree[i].resize(1);
             tree[i][0] = a[i-base];
         }
-        for (int i=base-1; i>=0; --i)
-        {
+        for (int i=base-1; i>=0; --i) {
             tree[i].resize(tree[i*2+1].size() + tree[i*2+2].size());
-            merge(tree[i*2+1].begin(), tree[i*2+1].end(), tree[i*2+2].begin(), tree[i*2+2].end(), tree[i].begin());
+            merge(all(tree[2*i+1]), all(tree[2*i+2]), tree[i].begin());
         }
     }
-    int qry_ub(int qs, int qe, int val)//[qs, qe]에서 val이하 몇개?
-    {
+    //[qs, qe]에서 val이하 몇개?
+    int qry_ub(int qs, int qe, int val) {
         int ret = 0;
         qs += base;
         qe += base+1;
-        for(; qs < qe; qs = qs / 2, qe = qe / 2)
-        {
-            if (qs%2 == 0)
-            {
-                ret += upper_bound(tree[qs].begin(), tree[qs].end(), val) - tree[qs].begin();
+        for(; qs < qe; qs = qs / 2, qe = qe / 2){
+            if (qs%2 == 0){
+                ret += upper_bound(all(tree[qs]), val) - tree[qs].begin();
                 ++qs;
             }
-            if (qe%2 == 0)
-            {
+            if (qe%2 == 0){
                 --qe;
-                ret += upper_bound(tree[qe].begin(), tree[qe].end(), val) - tree[qe].begin();
+                ret += upper_bound(all(tree[qe]), val) - tree[qe].begin();
             }
         }
         return ret;
     }
-    int qry_lb(int qs, int qe, int val)// [qs, qe]에서 val미만 몇개?
-    {
+    // [qs, qe]에서 val미만 몇개?
+    int qry_lb(int qs, int qe, int val){
         int ret = 0;
         qs += base;
         qe += base+1;
-        for(; qs < qe; qs = qs / 2, qe = qe / 2)
-        {
-            if (qs%2 == 0)
-            {
-                ret += lower_bound(tree[qs].begin(), tree[qs].end(), val) - tree[qs].begin();
+        for(; qs < qe; qs = qs / 2, qe = qe / 2){
+            if (qs%2 == 0){
+                ret += lower_bound(all(tree[qs]), val) - tree[qs].begin();
                 ++qs;
             }
-            if (qe%2 == 0)
-            {
+            if (qe%2 == 0){
                 --qe;
-                ret += lower_bound(tree[qe].begin(), tree[qe].end(), val) - tree[qe].begin();
+                ret += lower_bound(all(tree[qe]), val) - tree[qe].begin();
             }
         }
         return ret;
     }
-    int qry_kth(int l, int r, int k)//배열 a에서, [l,r]에 속하는 '값'들만 고려 했을 때, k번째 원소의 index를 반환
-    {
+    //배열 a에서, [l,r]에 속하는 '값'들만 고려 했을 때, k번째 원소의 index를 반환
+    int qry_kth(int l, int r, int k){
         int node = 0;
-        while(node < base)
-        {
-            int c = upper_bound(tree[node*2+1].begin(), tree[node*2+1].end(), r) -
-                    lower_bound(tree[node*2+1].begin(), tree[node*2+1].end(), l);
-            if (c >= k)
-            {
+        while(node < base){
+            int c = upper_bound(all(tree[node*2+1]), r) -
+                    lower_bound(all(tree[node*2+1]), l);
+            if (c >= k){
                 node = 2*node + 1;
             }
-            else
-            {
+            else{
                 node = 2*node + 2;
                 k -= c;
             }