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

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;

int a[200005];
int p[200005];
int n,m;

int lowbit(int x)
{
    return x&(-x);
}

void build()
{
    int i,j;
    for(i=1;i<=n;i++)
    {
        p[i]=a[i];
        for(j=1;j<lowbit(i);j<<=1)
        {
            if(p[i]<p[i-j])
                p[i]=p[i-j];
        }
    }
}

void insert(int i,int x)
{
    a[i]=x;
    while(i<=n)
    {
        if(p[i]<x)
            p[i]=x;
        else     break;

        i += lowbit(i);
    }
}

int query(int l,int r)
{
    int maxn=a[r];
    while(true)
    {
        if(maxn<a[r])
            maxn=a[r];
        if(l==r)   break;

        for(r-=1;r-l>=lowbit(r);r-=lowbit(r))
        {
            if(maxn<p[r])
                maxn=p[r];
        }
    }
    return maxn;
}

int main()
{
    while(~scanf("%d%d",&n,&m))
    {
        memset(p,0,sizeof p);
        int i;
        for(i=1;i<=n;i++)
            scanf("%d",a+i);
        build();

        char c[3];
        int x,y;
        for(i=1;i<=m;i++)
        {
            scanf("%s%d%d",c,&x,&y);

            if(c[0]=='Q')
                printf("%d\n",query(x,y));
            else
                insert(x,y);
        }
    }

    return 0;
}

HDUJ 1754 I Hate It,布布扣,bubuko.com

HDUJ 1754 I Hate It

原文：http://blog.csdn.net/hyccfy/article/details/38420771