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OI-codes/Luogu/P1522/P1522.cpp

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#include <bits/stdc++.h>
using namespace std;
int n, t;
double g[155][155], d[155], l1, l2 = 1e9, ans;
pair<int, int> m[155];
double dis(pair<int, int> a, pair<int, int> b) {
return sqrt(pow(a.first - b.first, 2) + pow(a.second - b.second, 2));
}
int main() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> m[i].first >> m[i].second;
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
scanf("%1d", &t);
if (t) {
g[i][j] = dis(m[i], m[j]);
} else {
g[i][j] = i == j ? 0 : 1e9;
}
}
}
for (int k = 1; k <= n; k++) {
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
g[i][j] = min(g[i][j], g[i][k] + g[k][j]);
}
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (g[i][j] != 1e9) {
d[i] = max(g[i][j], d[i]);
}
l1 = max(l1, d[i]);
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (g[i][j] == 1e9) {
l2 = min(l2, d[i] + dis(m[i], m[j]) + d[j]);
}
}
}
cout << fixed << setprecision(6) << max(l1, l2) << endl;
return 0;
}