1360E - Polygon - CodeForces Solution

// Problem: E. Polygon
// Contest: Codeforces - Codeforces Round #644 (Div. 3)
// URL: https://codeforces.com/contest/1360/problem/E
// Memory Limit: 256 MB
// Time Limit: 2000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<utility>
#include<set>
#include<unordered_set>
#include<list>
#include<iterator>
#include<deque>
#include<queue>
#include<stack>
#include<set>
#include<bitset>
#include<random>
#include<map>
#include<unordered_map>
#include<stdio.h>
#include<complex>
#include<math.h>
#include<cstring>
#include<chrono>
#include<string>

// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("no-stack-protector")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("sse,sse2,sse3,ssse3,popcnt,abm,mmx,tune=native")
// #pragma GCC optimize("fast-math") 

using namespace std;
#define pb push_back
#define ff first
#define ss second
#define vi vector <int>
#define vvi vector <vi>
#define pii pair<int, int>
#define ppi pair<pii, int>
#define vii vector<pii>
#define mii map<int, int>
#define mci map<char, int>
#define miv map<int, vi>
#define mis map<int, set<int>>
#define setbits(n) __builtin_popcount(n)
#define msb(x) __builtin_clz(x)
#define lsb(x) __builtin_ctz(x)
#define all(v) (v).begin(), (v).end()
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
#define endl "\n"
#define fo(i,n) for(int i=0;i<n;i++)
#define in(a,n)	for(int i=0;i<n;i++) cin>>a[i];
#define dbg(x) cout << #x << " = " << (x) << endl
#define show2(a, b) cout<<a<<' '<<b<<endl
#define show3(a, b, c) cout<<a<<' '<<b<<' '<<c<<endl
#define show(arr) for (auto i:arr) cout<<i<<' '; 
#define Endl endl
const long long N=1e5+5;
const long long mod=1000000007; //998244353;
//always use arrays if you want to coordinate compress.
vvi vis;
vector<string> s;
int n;
bool check(int x, int y)
{
	if(x==n || y==n)return true;
	if(vis[x][y]!=-1)return vis[x][y];
	if(s[x][y]!='1')return vis[x][y]=false;
	return vis[x][y]=(check(x+1,y)||check(x,y+1));
}
void cases(){
	cin>>n;
	s.clear();s.resize(n);in(s,n);
	vis.clear();vis.assign(n,vi(n,-1));
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<n;j++)
		{
			if(vis[i][j]==1 || s[i][j]=='0')continue;
			if(!check(i,j))
			{
				// show2(i,j);
				no;return;
			}
		}
	}
	yes;
}

int32_t main(){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    int t=1;
    cin>>t;
    for (int i=0; i<t; i++){
    	//cout<<"Case #"<<i+1<<": ";
		cases();
    }
    return 0;
}