题解 | 最大正方形

#include<bits/stdc++.h>
using namespace std;
struct node{
    int x,y;
};
int main(){
    char c[110][110];
    int ans[4][2];
    vector<node>a;
    int n;
    cin>>n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            cin>>c[i][j];
            if(c[i][j]=='#')a.push_back({i,j});
        }
    }
    int x1,x2,x3,x4,y1,y2,y3,y4,dx,dy,maxn=-1;
    int len=a.size();
    for(int i=0;i<len;i++){
        x1=a[i].x;
        y1=a[i].y;
        for(int j=i+1;j<len;j++){
            x2=a[j].x;
            y2=a[j].y;
            dx=x1-x2;
            dy=y1-y2;
                x3 = x1 + y2 - y1;
                y3 = y1 - (x2 - x1);
                x4 = x2 + y2 - y1;
                y4 = y2 - (x2 - x1);
                if(x3<1||x3>n||y3<1||y3>n||x4<1||x4>n||y4<1||y4>n)continue;
                if(c[x3][y3]=='#'&&c[x4][y4]=='#'){
                    int chang=dx*dx+dy*dy;
                    if(chang>maxn){
                        maxn=chang;
                        ans[0][0]=x1;
                        ans[0][1]=y1;
                        ans[1][0]=x2;
                        ans[1][1]=y2;
                        ans[2][0]=x3;
                        ans[2][1]=y3;
                        ans[3][0]=x4;
                        ans[3][1]=y4;
                }
            }
        }
    }
    for(int i=0;i<4;i++){
        for(int j=0;j<2;j++){
            cout<<ans[i][j]<<" ";
        }
        cout<<endl;
    }
}
// 64 位输出请用 printf("%lld")