POJ2796Feel Good[单调栈]

//
//  main.cpp
//  poj2796
//
//  Created by Candy on 10/5/16.
//  Copyright © 2016 Candy. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
typedef long long ll;
const int N=1e5+5;
inline int read(){
    char c=getchar();int x=0,f=1;
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
    return x;
}
int n;
ll a,ans=-1,ansb,anse;
struct data{
    ll h,l;
    int b;
}st[N];
int top=0;
int main(int argc, const char * argv[]) {
    n=read();
    for(int i=1;i<=n;i++){
        a=read();
        ll right=0;int b=i;
        while(top&&st[top].h>=a){
            ll tmp=(st[top].h*(st[top].l+right));
            right+=st[top].l;
            b=st[top].b;
            if(tmp>ans){
                ans=tmp;
                ansb=st[top].b;
                anse=i-1;//printf("t %lld %lld %lld\n",ans,ansb,anse);
            }
            top--;
        }
        top++;
        st[top].h=a;
        st[top].l=right+a;
        st[top].b=b;
    }
    ll right=0;
    while(top){
        ll tmp=(st[top].h*(st[top].l+right));
        right+=st[top].l;
        if(tmp>ans){
            ans=tmp;
            ansb=st[top].b;
            anse=n;
        }
        top--;
    }
    printf("%lld\n%lld %lld",ans,ansb,anse);
    return 0;
}