35 lines
836 B
C++
35 lines
836 B
C++
#include <bits/stdc++.h>
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using namespace std;
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const int N = 1e5 + 10, M = N << 1;
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int n, m;
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int h[N], e[M], ne[M], w[M], idx;
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int out[N];
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double f[N];
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void add(int a, int b, int c) {
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e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx++;
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}
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double dfs(int u) {
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if (f[u] >= 0) return f[u]; // 如果u点计算过，记忆化搜索返回结果值
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f[u] = 0; // 初始化为0，准备开始填充
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for (int i = h[u]; ~i; i = ne[i]) {
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int j = e[i];
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f[u] += (w[i] + dfs(j)) / out[u];
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}
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return f[u];
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}
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int main() {
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memset(h, -1, sizeof h);
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cin >> n >> m;
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while (m--) {
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int a, b, c;
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cin >> a >> b >> c;
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add(a, b, c);
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out[a]++;
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}
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memset(f, -1, sizeof f);
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printf("%.2lf\n", dfs(1));
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return 0;
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} |