1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
#include <iostream>
#include <vector>

using namespace std;

typedef pair<int, int> i2;

const int N = 409;
const int inf = 1e4+9;
string adj[N];
int D[N][N];
vector<i2> V[N];
i2 P[N*N];

void solve() {

    int n; cin >> n;
    for(int i = 0; i < n; ++i) {
        cin >> adj[i];
        V[i].clear();
    }
    for(int i = 1; i <= n; ++i) {
        for(int j = 1; j <= n; ++j) {
            if(adj[i-1][j-1] == '1')
                D[i][j] = 1;
            else
                D[i][j] = inf;
        }
        D[i][i] = 0;
    }
    for(int k = 1; k <= n; ++k) {
        for(int i = 1; i <= n; ++i) {
            for(int j = 1; j <= n; ++j) {
                D[i][j] = min(D[i][j], D[i][k] + D[k][j]);
            }
        }
    }
    /*for(int i = 1; i <= n; ++i) {
        for(int j = 1; j <= n; ++j) {
            cout << D[i][j] << " ";
        }
        cout << '\n';
    }*/
    for(int i = 1; i <= n-1; ++i) {
        for(int j = i+1; j <= n; ++j) {
            V[D[i][j]].push_back({i, j});
        }
    }
    int m = 0;
    for(int d = n-1; d >= 1; --d) {
        for(auto p : V[d]) {
            P[++m] = p;
        }
    }
    /*for(int i = 1; i <= m; ++i) {
        cout << P[i].first << " " << P[i].second << " ";
    }
    cout << "\n";*/
    int res = inf;
    for(int y = m; y >= 1; --y) {
        int a = P[y].first;
        int b = P[y].second;
        int max_d = 0;
        for(int x = 1; x <= m && max_d < res; ++x) {
            int i = P[x].first;
            int j = P[x].second;
            if(D[i][j] <= max_d) break;
            max_d = max(max_d, min(D[i][j], min(D[i][a] + D[b][j], D[i][b] + D[a][j])));
        }
        res = min(res, max_d);
    }
    /*for(int a = 1; a <= n-1; ++a) {
        for(int b = a+1; b <= n; ++b) {
            int max_d = 0;
            for(int x = 1; x <= m && max_d < res; ++x) {
                int i = P[x].first;
                int j = P[x].second;
                max_d = max(max_d, min(D[i][j], min(D[i][a] + D[b][j], D[i][b] + D[a][j])));
            }
            res = min(res, max_d);
        }
    }*/
    /*for(int a = 1; a <= n-1; ++a) {
        for(int b = a+1; b <= n; ++b) {
            int max_d = 0;
            for(int i = 1; i <= n-1 && max_d < res; ++i) {
                for(int j = i+1; j <= n && max_d < res; ++j) {
                    max_d = max(max_d, min(D[i][j], min(D[i][a] + D[b][j], D[i][b] + D[a][j])));
                }
            }
            res = min(res, max_d);
        }
    }*/
    cout << res << "\n";
}

int main() {

    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int t; cin >> t;
    while(t--) {
        solve();
    }

    return 0;
}