Lightoj1083【单调栈】

#include <cstdio>
#include <stack>
#include <iostream>
#include <string.h>
#include <algorithm>
using namespace std;
typedef long long LL;
const int N=5e4+10;
struct asd
{
    LL pre;
    LL next;
    LL num;
};
int n;
LL ww[N];

int main()
{
    int T,cas=1;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for(int i=1; i<=n; i++)
            scanf("%lld",&ww[i]);

        stack<asd>q;
        asd tmp;
        tmp.num=ww[1];
        tmp.next=tmp.pre=1;
        q.push(tmp);
        LL ans=0;
        for(int i=2; i<=n; i++)
        {
            asd tmp1;
            tmp1.num=ww[i];
            tmp1.pre=tmp1.next=1;
            while(!q.empty()&&tmp1.num<q.top().num)
            {
                tmp=q.top();
                q.pop();
                tmp1.pre+=tmp.pre;
                if(!q.empty())
                    q.top().next+=tmp.next;
                ans=max(tmp.num*(tmp.pre+tmp.next-1),ans);
            }
            q.push(tmp1);
        }

        while(!q.empty())
        {
            tmp=q.top();
            q.pop();
            if(!q.empty())
                q.top().next+=tmp.next;
            ans=max(ans,(tmp.next+tmp.pre-1)*tmp.num);
        }

        printf("Case %d: %lld\n",cas++,ans);
    }
    return 0;
}