2018ICPC南京赛区网络选拔B The writing on the wall (单调栈)

#2018ICPC南京赛区网络选拔B The writing on the wall (单调栈)
###题目链接：
https://nanti.jisuanke.com/t/30991
###代码：

#include<bits/stdc++.h>
using namespace std;
const int maxn=1e5+5;
#define push_back pb;
vector<int>Q[maxn];
pair<int,int>P[maxn];
int h[maxn];
int main()
{
    int n,m,T,i,j,k,s;
    long long ans;
    int x,y;
    scanf("%d",&T);
    for(s=1;s<=T;s++)
    {
        ans=0;
        scanf("%d%d%d",&m,&n,&k);
        for(i=1;i<=k;i++)
        {
            scanf("%d%d",&P[i].second,&P[i].first);
        }
        sort(P+1,P+1+k);
        int temp=1;
        memset(h,0,sizeof(h));
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=m;j++)
            {
                if(temp<=k&&P[temp].first==i&&P[temp].second==j)
                {
                    // cout<<"-------------"<<endl;
                    temp++;
                    h[j]=0;
                }
                else h[j]++;
            }
            int top=0;
            int sta[maxn];
            h[0]=0;
            sta[++top]=0;
            long long subans=0;
            for(j=1;j<=m;j++)
            {
                while(top>0&&h[j]<=h[sta[top]])
                {
                    subans-=1ll*h[sta[top]]*(sta[top]-sta[top-1]);
                    top--;
                }
                sta[++top]=j;
                subans+=1ll*h[sta[top]]*(sta[top]-sta[top-1]);
                ans+=subans;
            }
        }
        printf("Case #%d: %lld\n",s,ans);
    }
}