题解 | 明日DISCO

#include <iostream>
#include<vector>
#define ll long long
using namespace std;

int main() {
    int n;
    cin>>n;
    vector<vector<ll>>i(n+4,vector<ll>(n+4));
    for(int x=1;x<=n;x++){
        for(int y=1;y<=n;y++){
            cin>>i[x][y];
            if(i[x][y-1]<0&&i[x][y]<0&&i[x][y-1]!=0&&i[x][y]!=0||i[x-1][y]<0&&i[x][y]<0&&i[x-1][y]!=0&&i[x][y]!=0||i[x-1][y]>0&&i[x][y]>0&&i[x-1][y]!=0&&i[x][y]!=0||i[x-1][y]>0&&i[x][y]>0&&i[x][y]!=0&&i[x][y-1]!=0){
                cout<<"NO"<<endl;
                return 0;
            }
        }
    }
    cout<<"YES"<<endl;
    return 0;
}