35 lines
1.4 KiB
C++
35 lines
1.4 KiB
C++
// P2047 社交网络。正权、无向、简单、连通图；有序点对，排除端点。
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#include <bits/stdc++.h>
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using namespace std;
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using ll = long long;
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int main() {
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ios::sync_with_stdio(false); cin.tie(nullptr);
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int n, m; if (!(cin >> n >> m)) return 0;
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const ll INF = 1LL << 60;
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vector<vector<ll>> d(n, vector<ll>(n, INF));
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// 中间受限图的计数可能超过最终答案范围，从存储起即用浮点。
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vector<vector<long double>> cnt(n, vector<long double>(n, 0));
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for (int i = 0; i < n; ++i) d[i][i] = 0;
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for (int e = 0, u, v; e < m; ++e) {
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ll w; cin >> u >> v >> w; --u; --v;
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d[u][v] = d[v][u] = w; cnt[u][v] = cnt[v][u] = 1;
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}
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for (int k = 0; k < n; ++k) for (int i = 0; i < n; ++i) for (int j = 0; j < n; ++j) {
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if (i == k || j == k || i == j) continue;
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if (d[i][k] == INF || d[k][j] == INF) continue;
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ll nd = d[i][k]+d[k][j];
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long double ways = cnt[i][k]*cnt[k][j];
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if (nd < d[i][j]) { d[i][j] = nd; cnt[i][j] = ways; }
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else if (nd == d[i][j]) cnt[i][j] += ways;
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}
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cout << fixed << setprecision(3);
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for (int v = 0; v < n; ++v) {
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long double ans = 0;
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for (int s = 0; s < n; ++s) for (int t = 0; t < n; ++t) {
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if (s == t || s == v || t == v) continue;
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if (d[s][v]+d[v][t] == d[s][t]) ans += cnt[s][v]*cnt[v][t]/cnt[s][t];
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}
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cout << ans << '\n';
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}
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}
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