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
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
#include<algorithm>
#include<iostream>
#include<string>

#include<chrono>

#define REP(i,n) for(int i=0;i<(n);++i)
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)

using namespace std;

const int MAXN = 400, YEAR = 2025;

short D[1+MAXN][1+MAXN];
short g, mg, mg2, mi, mj, mk, h, h1, res, n, n1, tc, s, t;

string ss;

int main(void) {
	auto begin = chrono::high_resolution_clock::now();
	
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	cin >> tc;
	REP(nTC, tc) {

		cin >> n;
		n1 = n-1;
		REP(i, n) {
			cin >> ss;
			REP(j, n) D[i][j] = (ss[j] == '1' ? 1 : YEAR);
			D[i][i] = 0;
		}

		REP(k,n) REP(i, n) REP(j, n) {
			D[i][j] = min(D[i][j], static_cast<short>(D[i][k] + D[k][j]));
		}

		mg = D[0][0];
		REP(i,n) REP(j,n) mg = max(mg, D[i][j]);
		REP(i,n) REP(j,n) if (D[i][j] == mg) { mi = i; mj = j; }
		REP(k,n) if (D[mi][k] == (mg/2) && D[k][mj] == (mg-mg/2)) { mk = k; }
		mg2 = mg/2;

		res = YEAR;
		
		s = mi; t = mj; {
			g = mg2;			
			REP(i, n) {
				FOR(j, i+1, n1) {
					h = D[i][j];
					if (h <= g) continue;
					h1 = static_cast<short>(D[i][s]+D[t][j]);
					if (h1 < h) {
						h = h1;
						if (h <= g) continue;
					}
					h1 = static_cast<short>(D[i][t]+D[s][j]);
					if (h1 < h) {
						h = h1;
						if (h <= g) continue;
					}
					g = h;
				}
			}
			res = g;			
		}

		REP(s,n) { 
		  FOR(t,s+1,n1) {
			g = mg2;
			
			{ int i = mi, j = mj;
				h = D[i][j];
				h1 = static_cast<short>(D[i][s]+D[t][j]);
				if (h1 < h) h = h1;
				h1 = static_cast<short>(D[i][t]+D[s][j]);
				if (h1 < h) h = h1;
				if (h > g) {
					g = h;
					if (g > res) goto break2;
				}
			}			

			{ int i = mi, j = mk;
				h = D[i][j];
				h1 = static_cast<short>(D[i][s]+D[t][j]);
				if (h1 < h) h = h1;
				h1 = static_cast<short>(D[i][t]+D[s][j]);
				if (h1 < h) h = h1;
				if (h > g) {
					g = h;
					if (g > res) goto break2;
				}
			}			

			{ int i = mk, j = mj;
				h = D[i][j];
				h1 = static_cast<short>(D[i][s]+D[t][j]);
				if (h1 < h) h = h1;
				h1 = static_cast<short>(D[i][t]+D[s][j]);
				if (h1 < h) h = h1;
				if (h > g) {
					g = h;
					if (g > res) goto break2;
				}
			}			
			
			REP(i, n) {
				FOR(j, i+1, n1) {
					h = D[i][j];
					if (h <= g) continue;
					h1 = static_cast<short>(D[i][s]+D[t][j]);
					if (h1 < h) {
						h = h1;
						if (h <= g) continue;
					}
					h1 = static_cast<short>(D[i][t]+D[s][j]);
					if (h1 < h) {
						h = h1;
						if (h <= g) continue;
					}
					g = h;
					if (g > res) goto break2;
				}
			}
			if (g < res) res = g;
			break2: ;
		  }
		  
		  auto end = chrono::high_resolution_clock::now();    
		  auto dur = end - begin;
		  auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(dur).count();
		  if (ms > 4800) break;
		}
		cout << res << endl;	
	}
	
	//auto end = chrono::high_resolution_clock::now();    
	//auto dur = end - begin;
	//auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(dur).count();
	//cerr << "milis = " << ms << endl;
	
	return 0;
}