I Hate It

5 6
1 2 3 4 5
Q 1 5
U 3 6
Q 3 4
Q 4 5
U 2 9
Q 1 5

5
6
5
9

Hint
Huge input,the C function scanf() will work better than cin

线段树，感觉比树状数组复杂多了，不过总算能轻松点AC模板题了，1200MS很无奈，希望以后会优化吧

#include<iostream>
#include<cstring>
#include<cstdio>
#define M 500010
using namespace std;

int n,m;
struct H
{
    int mi,ma,sum,l,r;
}trees[M];
int num[M];

void build_trees(int jd,int l,int r)
{
    trees[jd].l=l;trees[jd].r=r;
    if(l==r)
        {trees[jd].ma=num[l];return ;}
    int mid=(l+r)/2;
    build_trees(jd*2,l,mid);
    build_trees(jd*2+1,mid+1,r);
    trees[jd].ma=max(trees[jd*2].ma,trees[jd*2+1].ma);
}

int query(int jd,int l,int r)
{
    int ans=0;
    if(l<=trees[jd].l&&r>=trees[jd].r)
        return trees[jd].ma;
    int mid=(trees[jd].l+trees[jd].r)/2;
    if(l<=mid) ans=max(ans,query(jd*2,l,r));
    if(r>mid)  ans=max(ans,query(jd*2+1,l,r));
    return ans;
}

void update(int jd,int l,int a)
{
    if(trees[jd].l==trees[jd].r)
        {trees[jd].ma=a;return;}
    int mid = (trees[jd].l+trees[jd].r)/2;
    if(l<=mid) update(jd*2,l,a);
    else update(jd*2+1,l,a);
    trees[jd].ma=max(trees[jd*2].ma,trees[jd*2+1].ma);
}

int main()
{
    int i,j;
    int a,b;
    char c[1];
    while(~scanf("%d%d",&n,&m))
    {
        memset(num,0,sizeof num);

        for(i=1;i<=n;i++)
            scanf("%d",&num[i]);
        build_trees(1,1,n);
        for(i=1;i<=m;i++)
        {
            scanf("%s%d%d",c,&a,&b);
            if(c[0]=='Q')
            {
                printf("%d\n",query(1,a,b));
            }
            if(c[0]=='U')
            {
                update(1,a,b);
            }
        }
    }
    return 0;
}

HDU 1754 I Hate It,布布扣,bubuko.com

HDU 1754 I Hate It

原文：http://blog.csdn.net/hanhai768/article/details/37885337