G

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 const int N=1010;
 6 int f[N],n;
 7 
 8 int Find(int x)
 9 {
10     return (x==f[x])?x:(f[x]=Find(f[x]));
11 }
12 
13 
14 int main()
15 {
16     freopen("bs.in","r",stdin);
17     int t;
18     scanf("%d",&t);
19     while (t--) {
20         scanf("%d",&n);
21         bool flag=1;
22         for (int i=0;i<n;i++) f[i]=i;
23         for (int i=0;i<n;i++) {
24             for (int j=0;j<n;j++) {
25                 int k;
26                 scanf("%d",&k);
27                 if (i==j&&k%2==0) {
28                     flag=0;
29                 }
30                 int x=Find(i),y=Find(j);
31                 if (k&&x!=y) f[x]=y;
32             }
33         }
34         if (!flag) {
35             printf("No\n");
36             continue;
37         }
38         for (int i=1;i<n;i++) {
39             if (Find(i)!=Find(0)) {
40                 flag=0;
41                 break;
42             }
43         }
44         if (flag) printf("Yes\n");
45         else printf("No\n");
46     }
47     return 0;
48 }