【BZOJ 1036】【ZJOI 2008】樹的統計

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此題為樹鏈剖分的裸題。 代碼如下，使用常用的輕重鏈剖分。

/**************************************************************Problem: 1036User: EvensgnLanguage: C++Result: AcceptedTime:2468 msMemory:5772 kb****************************************************************/#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <cstdlib>using namespace std;const int MaxE = 30000 + 5, MaxN = 30000 + 5;int n, q, topH, W[MaxN], f[MaxN], dep[MaxN], top[MaxN], son[MaxN], h[MaxN], size[MaxN], A[MaxN];int Ans;struct treeNode{int sum, max;} T[MaxN * 4];struct edge {int u, v;edge *next;} E[MaxE * 2], *P = E, *point[MaxN];inline void addedge(int x, int y){++P; P -> u = x; P -> v = y; P -> next = point[x]; point[x] = P;}int DFS_1(int now, int depth, int fa){f[now] = fa;dep[now] = depth;int sonSize, maxSonSize = 0;size[now] = 1;for (edge *j = point[now]; j; j = j -> next){if (j -> v != f[now]){sonSize = DFS_1(j -> v, depth + 1, now);size[now] += sonSize;if (maxSonSize < sonSize) {son[now] = j -> v;maxSonSize = sonSize;}}}return size[now];}void DFS_2(int now){if (now != son[f[now]]) top[now] = now;else top[now] = top[f[now]];h[now] = ++topH;A[h[now]] = W[now];if (son[now]) DFS_2(son[now]);for (edge *j = point[now]; j; j = j -> next)if (j -> v != son[now] && j -> v != f[now]) DFS_2(j -> v);}int max(int a, int b){if (a > b) return a;return b;}void update(int x){T[x].sum = T[x * 2].sum + T[x * 2 + 1].sum;T[x].max = max(T[x * 2].max, T[x * 2 + 1].max);}void buildTree(int x, int s, int t){if (s == t){T[x].sum = A[s];T[x].max = A[s];return;}int m = (s + t) >> 1;buildTree(x * 2, s, m);buildTree(x * 2 + 1, m + 1, t);update(x);}void change(int x, int s, int t, int loc, int num){if (s == t){T[x].sum = num;T[x].max = num;return;}int m = (s + t) >> 1;if (loc <= m) change(x * 2, s, m, loc, num);else change(x * 2 + 1, m + 1, t, loc, num);update(x);}int getMax(int x, int s, int t, int l, int r){if (l <= s && r >= t)return T[x].max;int m = (s + t) >> 1, ans = -999999999;if (l <= m) ans = max(ans, getMax(x * 2, s, m, l, r));if (r >= m + 1) ans = max(ans, getMax(x * 2 + 1, m + 1, t, l, r));return ans;}int getSum(int x, int s, int t, int l, int r){if (l <= s && r >= t)return T[x].sum;int m = (s + t) >> 1, ans = 0;if (l <= m) ans += getSum(x * 2, s, m, l, r);if (r >= m + 1) ans += getSum(x * 2 + 1, m + 1, t, l, r);return ans;}void queryMax(int s, int t){int f1, f2;f1 = 0; f2 = 1;while (f1 != f2){f1 = top[s];f2 = top[t];if (f1 != f2){if (dep[f1] >= dep[f2]){Ans = max(Ans, getMax(1, 1, n, h[f1], h[s]));s = f[f1];}else {Ans = max(Ans, getMax(1, 1, n, h[f2], h[t]));t = f[f2];}}else{if (s == t) Ans = max(Ans, getMax(1, 1, n, h[s], h[s]));else {if (dep[s] >= dep[t]) Ans = max(Ans, getMax(1, 1, n, h[t], h[s]));else Ans = max(Ans, getMax(1, 1, n, h[s], h[t]));}}}}void querySum(int s, int t){int f1, f2;f1 = 0; f2 = 1;while (f1 != f2){f1 = top[s];f2 = top[t];if (f1 != f2){if (dep[f1] >= dep[f2]){Ans += getSum(1, 1, n, h[f1], h[s]);s = f[f1];}else {Ans += getSum(1, 1, n, h[f2], h[t]);t = f[f2];}}else{if (s == t) Ans += getSum(1, 1, n, h[s], h[s]);else {if (dep[s] >= dep[t]) Ans += getSum(1, 1, n, h[t], h[s]);else Ans += getSum(1, 1, n, h[s], h[t]);}}}}int main(){//freopen("1.in", "r", stdin);scanf("%d", &n);int a, b;char flag[10];for (int i = 1; i <= n - 1; i++){scanf("%d%d", &a, &b);addedge(a, b);addedge(b, a);}for (int i = 1; i <= n; i++) scanf("%d", &W[i]);DFS_1(1, 1, 0);topH = 0; top[1] = 1; DFS_2(1);buildTree(1, 1, n);scanf("%d", &q);for (int i = 1; i <= q; i++){scanf("%s%d%d", flag, &a, &b);if (!strcmp(flag, "QMAX")){Ans = -999999999;queryMax(a, b);printf("%d\n", Ans);}else if (!strcmp(flag, "QSUM")){Ans = 0;querySum(a, b);printf("%d\n", Ans);}else         //Change one node{change(1, 1, n, h[a], b);}}return 0;}