Feel Good POJ - 2796

#include <iostream>
#include <stack>
#include <cstdio>
using namespace std;
#define ll long long
const int N = 100010;
ll ans,minv = -1,s[N];
int l[N],r[N],a[N];
int main()
{//不能在while循环里计算最大权值,因为会漏掉 比如6 6 5 6 4 5 当计算最大 权值时会漏掉最左的6,所有应该是取出栈后的下标 
    freopen("in.txt","r",stdin);
    int n,j;
    stack<int> stk;
    scanf("%d",&n);
    for(int i=1;i<=n;i++) { scanf("%d",&a[i]);s[i] = s[i-1]+1ll*a[i]; } 
    for(int i=1;i<=n;i++){
        bool flag = true;
        while(!stk.empty()&&a[stk.top()]>=a[i]) stk.pop();
        if(stk.empty()) l[i] = 0;
        else l[i] = stk.top();
        stk.push(i);
    }
    while(!stk.empty()) stk.pop();
    for(int i=n;i>0;i--){
        while(!stk.empty()&&a[stk.top()]>=a[i]) stk.pop();
        if(stk.empty()) r[i] = n;
        else r[i] = stk.top()-1;
        stk.push(i);
    }
    for(int i=1;i<=n;i++){
        ans = (ll)(s[r[i]]-s[l[i]])*a[i];
        if(ans>minv){
            minv = ans;
            j = i;
        }
    }
    printf("%lld\n%d %d",minv,l[j]+1,r[j]);
    return 0;
}