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45 lines
967 B
45 lines
967 B
#include <bits/stdc++.h>
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using namespace std;
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const int N = 210, M = 30010;
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int n, m;
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int g[N][N], st[N];
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int match[N];
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int dfs(int x) {
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for (int i = 1; i <= n; i++) {
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if (g[x][i] && !st[i]) {
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st[i] = 1;
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int t = match[i];
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if (t == -1 || dfs(t)) {
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match[i] = x;
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return 1;
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}
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}
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}
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return 0;
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}
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int main() {
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memset(match, -1, sizeof match);
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scanf("%d %d", &n, &m);
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while (m--) {
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int a, b;
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scanf("%d %d", &a, &b);
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g[a][b] = 1;
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}
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// floyd求传递闭包
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for (int k = 1; k <= n; k++)
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for (int i = 1; i <= n; i++)
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for (int j = 1; j <= n; j++)
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g[i][j] |= g[i][k] & g[k][j];
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int res = 0;
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for (int i = 1; i <= n; i++) {
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memset(st, 0, sizeof st);
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if (dfs(i)) res++;
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}
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printf("%d\n", n - res);
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return 0;
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} |