Hdu 1754——I Hate It

线段树

单点更新

#include<cstdio>#include<iostream>using namespace std;struct Node{int left;int right;int max;}node[200000*4];int Max(int a,int b){return a>b?a:b;}void TreeMake(int l,int r,int i){node[i].left=l;node[i].right=r;node[i].max=0;if(l==r)return ;int m=(l+r)>>1;TreeMake(l,m,i<<1);TreeMake(m+1,r,i<<1|1);}void TreeUpdate(int x,int s,int i){int l=node[i].left;int r=node[i].right;int m=(l+r)>>1;if(l==x&&r==x){node[i].max=s;return ;}if(node[i].max<s){node[i].max=s;}if(x<=m)TreeUpdate(x,s,i<<1);elseTreeUpdate(x,s,i<<1|1);}int TreeQuery(int x,int y,int i){int l=node[i].left;int r=node[i].right;int m=(l+r)>>1;int ans=0;if(x==l&&y==r)return node[i].max;if(y<=m){ans=TreeQuery(x,y,i<<1);}else{if(x>m)ans=TreeQuery(x,y,i<<1|1);elseans=Max(TreeQuery(x,m,i<<1),TreeQuery(m+1,y,i<<1|1));}return ans;}int main(){int n,m;while(~scanf("%d%d",&n,&m)){TreeMake(1,n,1);int temp;for(int i=1;i<=n;i++){scanf("%d",&temp);TreeUpdate(i,temp,1);}char ch;int x,y;for(int i=0;i<m;i++){getchar();scanf("%c %d %d",&ch,&x,&y);if(ch=='Q'){printf("%d\n",TreeQuery(x,y,1));}else{TreeUpdate(x,y,1);}}}return 0;}