HDU-1754 I Hate It

来源：互联网发布：谷歌开源图片压缩算法编辑：程序博客网时间：2024/05/16 18:24

题目链接：https://vjudge.net/problem/HDU-1754

用线段树模板来做，把每个节点由储存子节点和改为储存子节点最大值就可以了

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>using namespace std;#define maxn 200000struct node{    int l, r, sum;    int mid(){        return (l+r)>>1;    }};node Tree[maxn<<2];int value[maxn+10];int flag;//初始化树，根节点是1void init_tree(int root, int l, int r){    Tree[root].l = l;    Tree[root].r = r;    if(l == r)        Tree[root].sum = value[l];    else{        init_tree(root<<1, l, (l+r)>>1);        init_tree((root<<1)+1, ((l+r)>>1) + 1, r);        Tree[root].sum = max(Tree[root<<1].sum , Tree[(root<<1)+1].sum);    }}//查找和int query_tree(int root, int l, int r){    int m = Tree[root].mid();    if(l == Tree[root].l && r == Tree[root].r)        return Tree[root].sum;    else{        if(l > m)            return query_tree((root<<1)+1, l, r);        else if(r <= m)            return query_tree(root<<1, l, r);        else            return max(query_tree(root<<1, l, m) , query_tree((root<<1)+1, m+1, r));    }}void update_tree(int root, int idx, int v){    if(Tree[root].l == Tree[root].r)        Tree[root].sum = v;    else{                if(idx <= Tree[root].mid())            update_tree(root<<1, idx, v);        else            update_tree((root<<1)+1, idx, v);           Tree[root].sum = max(Tree[root<<1].sum,Tree[(root<<1)+1].sum);     }}int main(){int n,m;while(~scanf("%d%d",&n,&m)){for(int i=1;i<=n;i++)scanf("%d",&value[i]);init_tree(1,1,n);int a,b;char c[5];for(int i=0;i<m;i++){scanf("%s%d%d",c,&a,&b);if(c[0]=='Q'){printf("%d\n",query_tree(1,a,b));}else{update_tree(1,a,b);}}}return 0;}

阅读全文

0 0