I Hate It

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C - I Hate It

#include<stdio.h>#include<iostream>#include<algorithm>using namespace std;struct node{int l, r, sum,_max;}dp[200005*4];void Creat(int l, int r, int i)//初始化线段树{dp[i].l = l;dp[i].r = r;dp[i].sum = dp[i]._max = 0;if (l == r)//当为最小子区间时输入值{scanf("%d", &dp[i].sum);dp[i]._max = dp[i].sum;return;}int mid = (l + r) / 2;//分半Creat(l, mid, i * 2);Creat(mid + 1, r, i * 2 + 1);dp[i]._max = max(dp[i * 2]._max, dp[i * 2 + 1]._max);//第i层的最大值更新}void Change(int a, int b, int i)//将第a个位置改成b{if (dp[i].l == dp[i].r){dp[i]._max = b;return;}int mid = (dp[i].l + dp[i].r) / 2;if (a <= mid){Change(a, b, i * 2);}else{Change(a, b, i * 2 + 1);}dp[i]._max = max(dp[i * 2]._max, dp[i * 2 + 1]._max);//修改值}int Find(int l, int r, int i){if (l == dp[i].l&&dp[i].r == r){return dp[i]._max;}int mid = (dp[i].l + dp[i].r) / 2;if (r <= mid){return Find(l, r, i * 2);}else if (l > mid){return Find(l, r, i * 2 + 1);}else{return max(Find(l, mid, i * 2), Find(mid + 1, r, i * 2 + 1));}}int main(){int n, m;while (cin >> n >> m){Creat(1, n, 1);char st[2];for (int i = 0; i < m; i++){scanf("%s", st);int a, b;scanf("%d%d", &a, &b);if (st[0] == 'Q'){cout << Find(a, b, 1) << endl;}else{Change(a, b, 1);}}}return 0;}
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