[置顶] HDU 1754 线段树

#include<iostream>

#include<string>

#include<cstring>

#include<algorithm>

#include<cstdio>

#include<cmath>

#include<cctype>

#include<iomanip>



#define Lson  left , t   , rt<<1

#define Rson  t+1  ,right,rt<<1|1



using namespace std;

const int maxn=200005;

int f[maxn<<2];



void PushUP( int rt ){

    f[rt] = max( f[rt<<1], f[rt<<1|1] );

}



void build( int left, int right ,int rt ){

    if( left==right ){

        cin>>f[rt];

        return;

    }

    int t=(left + right)>>1;

    build(Lson);

    build(Rson);

    PushUP(rt);

}



void update(int ii,int value,int left, int right, int rt ){

    if( left == right ){

        f[rt] = value; return;

    }

    int t=(left+right)>>1;

    if(ii<=t) update(ii, value, Lson);

    else      update(ii, value, Rson);

    PushUP(rt);

}



int query(int l, int r, int left, int right, int rt ){

    if( l<=left && r>=right )

        return f[rt];

    int t=(left+right)/2;

    int ret = 0;

    if(l <= t)ret = max(ret, query( l, r, Lson) );

    if(r > t) ret = max(ret, query( l, r, Rson) );

    return ret;

}



int main(){

    int n,m;

    while(cin>>n>>m){

        build(1,n,1);

        while(m--){

            char C; int a,b;//for(int i=0;i<=n;++i)cout<<f[i]<<' ';cout<<endl;

            cin>>C>>a>>b;

            if(C=='Q') cout<<query(a,b,1,n,1)<<endl;

            else update(a,b,1,n,1);

        }

    }

    return 0;

}