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
#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

const int N = 405;

int d[N][N];
char s[N];

int main() {
    int t;
    scanf("%d", &t);
    while (t--) {
        int n;
        scanf("%d", &n);
        for (int i = 0; i < n; i++) {
            scanf("%s", s);
            for (int j = 0; j < n; j++) {
                if (i == j) {
                    continue;
                }
                if (s[j] - '0' == 1) {
                    d[i][j] = 1;
                } else {
                    d[i][j] = n;
                }
            }
        }

        for (int k = 0; k < n; k++) {
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
                }
            }
        }
        vector<pair<int, int>> pairs;
        for (int i = 0; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                pairs.emplace_back(i, j);
            }
        }

        sort(pairs.begin(), pairs.end(),
             [&](pair<int, int> a, pair<int, int> b) {
                 return d[a.first][a.second] > d[b.first][b.second];
             });

        int best = n;

        for (int a = 0; a < n; a++) {
            for (int b = a + 1; b < n; b++) {
                int dia = 0;
                for (const auto &[u, v] : pairs) {
                    if (d[u][v] <= dia) {
                        break;
                    }
                    int dd = min(d[u][v], d[u][a] + d[b][v]);
                    dd = min(dd, d[u][b] + d[a][v]);
                    dia = max(dia, dd);
                    if (dia >= best) {
                        break;
                    }
                }
                best = min(best, dia);
            }
        }

        printf("%d\n", best);
    }

    return 0;
}

// g++ -std=c++17 -Wall -Wextra -Wshadow A.cpp -o A