#include<bits/stdc++.h> int main(){ using namespace std; ios::sync_with_stdio(false), cin.tie(nullptr); //~ freopen("tel2.in", "r", stdin); int tt; cin >> tt; while(tt--){ int n; cin >> n; const int inf = (int)1e9; vector<vector<int>> d(n, vector<int> (n, inf)); for(int a = 0;a < n;a++){ for(int b = 0;b < n;b++){ char c; cin >> c; if(c == '1') d[a][b] = 1; } d[a][a] = 0; } if(n <= 2){ cout << 0 << '\n'; continue; } // grupy[i] -> jak będą wygłądał graf po usunięciu i. vector<vector<vector<int>>> grupy(n); for(int c = 0;c < n;c++){ for(int a = 0;a < n;a++){ for(int b = 0;b < n;b++){ d[a][b] = min(d[a][b], d[a][c] + d[c][b]); } } } for(int a = 0;a < n;a++){ // usuwamy a vector<int> vis(n); vis[a] = 1; for(int b = 0;b < n;b++){ if(vis[b]) continue; //~ cerr << "b: " << b << endl; vector<int> v; queue<int> que; vis[b] = 1; que.push(b); while(!que.empty()){ int x = que.front(); que.pop(); v.push_back(x); for(int i = 0;i < n;i++){ if(!vis[i] && d[x][i] == 1){ vis[i] = 1; que.push(i); } } } int max_dist = 0; for(int _a : v) for(int _b : v) max_dist = max(max_dist, d[_a][_b]); v.push_back(max_dist); grupy[a].push_back(v); } } //~ for(int a = 0;a < n;a++){ //~ cerr << "a: " << a << endl; //~ for(const vector<int> &g : grupy[a]){ //~ cerr << " { "; //~ for(int x : g) cerr << x << ' '; //~ cerr << " } "; //~ } //~ cerr << endl; //~ } int ans = inf; { // coś co może ma sens i jakoś na to wpadłem for(int a = 0;a < n;a++){ for(int b = a + 1;b < n;b++){ // (a, b) // there is also a case where furthest pair is inside some group. // how to find this one ? int cur_ans = 0; vector<vector<int>> common_groups; pair<int, int> max_alone = {0, 0}; auto upd = [&](int x)->void{ if(x >= max_alone.first){ max_alone.second = max_alone.first; max_alone.first = x; return ; } if(x >= max_alone.second) max_alone.second = x; }; for(vector<int> &g : grupy[a]){ int Z = g.back(); g.pop_back(); bool found_b = false; int max_dist = 0; for(int x : g){ max_dist = max(max_dist, d[a][x]); if(x == b) found_b = true; } if(found_b) common_groups.push_back(g); else { upd(max_dist); cur_ans = max(cur_ans, Z); } g.push_back(Z); } for(vector<int> &g : grupy[b]){ int max_dist = 0; int Z = g.back(); g.pop_back(); bool found_a = false; for(int x : g){ if(x == a){ found_a = true; break; } max_dist = max(max_dist, d[x][b]); } if(!found_a){ upd(max_dist); cur_ans = max(cur_ans, Z); } g.push_back(Z); } int max_common = 0; //~ assert((int)common_groups.size() == 1); int who = -1; for(const vector<int> &g : common_groups){ int max_dist = 0; for(int x : g){ if(min(d[x][a], d[x][b]) > max_dist){ who = x; } max_dist = max(max_dist, min(d[x][a], d[x][b])); } max_common = max(max_common, max_dist); } cur_ans = max(cur_ans, max_alone.first + max_alone.second); cur_ans = max(cur_ans, max_alone.first + max_common); if(who != -1){ const vector<int> &g = common_groups.back(); for(int x : g){ cur_ans = max(cur_ans, d[x][who]); } } ans = min(ans, cur_ans); } } } cout << ans << '\n'; } return 0; } /* 2 4 0111 1011 1101 1110 5 01000 10100 01010 00101 00010 */
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 | #include<bits/stdc++.h> int main(){ using namespace std; ios::sync_with_stdio(false), cin.tie(nullptr); //~ freopen("tel2.in", "r", stdin); int tt; cin >> tt; while(tt--){ int n; cin >> n; const int inf = (int)1e9; vector<vector<int>> d(n, vector<int> (n, inf)); for(int a = 0;a < n;a++){ for(int b = 0;b < n;b++){ char c; cin >> c; if(c == '1') d[a][b] = 1; } d[a][a] = 0; } if(n <= 2){ cout << 0 << '\n'; continue; } // grupy[i] -> jak będą wygłądał graf po usunięciu i. vector<vector<vector<int>>> grupy(n); for(int c = 0;c < n;c++){ for(int a = 0;a < n;a++){ for(int b = 0;b < n;b++){ d[a][b] = min(d[a][b], d[a][c] + d[c][b]); } } } for(int a = 0;a < n;a++){ // usuwamy a vector<int> vis(n); vis[a] = 1; for(int b = 0;b < n;b++){ if(vis[b]) continue; //~ cerr << "b: " << b << endl; vector<int> v; queue<int> que; vis[b] = 1; que.push(b); while(!que.empty()){ int x = que.front(); que.pop(); v.push_back(x); for(int i = 0;i < n;i++){ if(!vis[i] && d[x][i] == 1){ vis[i] = 1; que.push(i); } } } int max_dist = 0; for(int _a : v) for(int _b : v) max_dist = max(max_dist, d[_a][_b]); v.push_back(max_dist); grupy[a].push_back(v); } } //~ for(int a = 0;a < n;a++){ //~ cerr << "a: " << a << endl; //~ for(const vector<int> &g : grupy[a]){ //~ cerr << " { "; //~ for(int x : g) cerr << x << ' '; //~ cerr << " } "; //~ } //~ cerr << endl; //~ } int ans = inf; { // coś co może ma sens i jakoś na to wpadłem for(int a = 0;a < n;a++){ for(int b = a + 1;b < n;b++){ // (a, b) // there is also a case where furthest pair is inside some group. // how to find this one ? int cur_ans = 0; vector<vector<int>> common_groups; pair<int, int> max_alone = {0, 0}; auto upd = [&](int x)->void{ if(x >= max_alone.first){ max_alone.second = max_alone.first; max_alone.first = x; return ; } if(x >= max_alone.second) max_alone.second = x; }; for(vector<int> &g : grupy[a]){ int Z = g.back(); g.pop_back(); bool found_b = false; int max_dist = 0; for(int x : g){ max_dist = max(max_dist, d[a][x]); if(x == b) found_b = true; } if(found_b) common_groups.push_back(g); else { upd(max_dist); cur_ans = max(cur_ans, Z); } g.push_back(Z); } for(vector<int> &g : grupy[b]){ int max_dist = 0; int Z = g.back(); g.pop_back(); bool found_a = false; for(int x : g){ if(x == a){ found_a = true; break; } max_dist = max(max_dist, d[x][b]); } if(!found_a){ upd(max_dist); cur_ans = max(cur_ans, Z); } g.push_back(Z); } int max_common = 0; //~ assert((int)common_groups.size() == 1); int who = -1; for(const vector<int> &g : common_groups){ int max_dist = 0; for(int x : g){ if(min(d[x][a], d[x][b]) > max_dist){ who = x; } max_dist = max(max_dist, min(d[x][a], d[x][b])); } max_common = max(max_common, max_dist); } cur_ans = max(cur_ans, max_alone.first + max_alone.second); cur_ans = max(cur_ans, max_alone.first + max_common); if(who != -1){ const vector<int> &g = common_groups.back(); for(int x : g){ cur_ans = max(cur_ans, d[x][who]); } } ans = min(ans, cur_ans); } } } cout << ans << '\n'; } return 0; } /* 2 4 0111 1011 1101 1110 5 01000 10100 01010 00101 00010 */ |