【BZOJ1191】[HNOI2006]超级英雄Hero【二分图匹配】

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【题目链接】

无法匹配的时候break就好了。

/* Pigonometry */#include <cstdio>#include <algorithm>using namespace std;const int maxn = 1005;int n, m, head[maxn], cnt, from[maxn], vis[maxn], clo;struct _edge {int v, next;} g[maxn << 1];inline int iread() {int f = 1, x = 0; char ch = getchar();for(; ch < '0' || ch > '9'; ch = getchar()) f = ch == '-' ? -1 : 1;for(; ch >= '0' && ch <= '9'; ch = getchar()) x = x * 10 + ch - '0';return f * x;}inline void add(int u, int v) {g[cnt] = (_edge){v, head[u]};head[u] = cnt++;}inline bool hungary(int x) {for(int i = head[x]; ~i; i = g[i].next) if(vis[g[i].v] != clo) {vis[g[i].v] = clo;if(!from[g[i].v] || hungary(from[g[i].v])) {from[g[i].v] = x;return 1;}}return 0;}int main() {n = iread(); m = iread();for(int i = 1; i <= n; i++) head[i] = -1; cnt = 0;for(int i = 1; i <= m; i++) {int a = iread(), b = iread(); a++; b++;add(i, a);if(a ^ b) add(i, b);}int ans = 0;for(int i = 1; i <= m; i++) {clo++;if(hungary(i)) ans++;else break;}printf("%d\n", ans);return 0;}

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