【Luogu】P1578奶牛浴场（DP，枚举）

　　题目链接

　　枚举极大子矩形。详情请见本题题解：I_AM_HelloWord

　　代码如下

　　

#include<cstdio>
#include<cctype>
#include<algorithm>
inline long long read(){
    long long num=,f=;
    char ch=getchar();
    while(!isdigit(ch)){
        if(ch=='-')    f=-;
        ch=getchar();
    }
    while(isdigit(ch)){
        num=num*+ch-'';
        ch=getchar();
    }
    return num*f;
}

struct Que{
    int y,x;
    bool operator <(const Que a)const{
        return y<a.y;
    }
}point[];

int ans;

int main(){
    int L=read(),W=read(),n=read();
    point[]=(Que){,};
    point[]=(Que){,L};
    point[]=(Que){W,};
    point[]=(Que){W,L};
    for(int i=;i<=n;++i)    point[i+]=(Que){read(),read()};
    n+=;
    std::sort(point+,point+n+);
    for(int i=;i<=n;++i){
        int l=point[i].y,r=L,u=,d=W;
        for(int j=i+;j<=n;++j){
            r=point[j].y;
            ans=std::max(ans,(r-l)*(d-u));
            if(point[j].x==point[i].x)    break;
            else if(point[j].x>point[i].x)    d=std::min(d,point[j].x);
            else u=std::max(u,point[j].x);
            r=L;
        }
    }
    printf("%d",ans);
    return ;
}