HDU-2389 Rain on your Parade

数据较大，用成Hopcroft-Karp算法更合适。

其实Hopcroft-Karp算法就是一开始通过DFS预处理出Dist标号，然后利用Dist标号实现同时查找多条最短增广路的目的。

#include <cstdlib>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <fstream>
#include <iostream>
#include <queue>

#define rep(i, l, r) for(int i=l; i<=r; i++)
#define clr(x, c) memset(x, c, sizeof(x))
#define N 3456
#define MAX 1<<30

using namespace std;
int read()
{
	int x=0, f=1; char ch=getchar();
	while (ch<'0' || ch>'9') { if (ch=='-') f=-1; ch=getchar(); }
	while (ch>='0' && ch<='9') { x=x*10+ch-'0'; ch=getchar(); }
	return x*f;
}

struct edge{int y, n;} e[N*N]; int fir[N], en;
struct node{int x, y, s;} g[N];
int n, m, t, ans, k[N*2], d[N*2];
int c[N*2];

void Add(int x, int y) { en++, e[en].y=y, e[en].n=fir[x], fir[x]=en; }

int Dist(int x1, int x2, int y1, int y2) { return (x2-x1)*(x2-x1)+(y1-y2)*(y1-y2); }

bool Find(int x)
{
	int o=fir[x], y=e[o].y;
	while (o)
	{
		if (!k[y] || (k[y] && d[x]==d[k[y]]-2 && Find(k[y]))) { k[y]=x; return true; }
		o=e[o].n, y=e[o].y;
	}
	return false;
}

int main()
{
	int tt=0, T=read();
	while (tt++ < T)
	{
		clr(fir, 0); clr(k, 0); en=ans=0; clr(c, 0);
		t=read(); n=read(); rep(i, 1, n) g[i].x=read(), g[i].y=read(), g[i].s=read()*t;
		m=read(); rep(j, 1, m) 
		{
			int x=read(), y=read();
			rep(i, 1, n) if (Dist(g[i].x, x, g[i].y, y) <= g[i].s*g[i].s) Add(i, j+N);
		}
		while (ans<n)
		{
			queue <int> q; bool can=true;
			rep(i, 1, n) if (!c[i]) q.push(i), d[i]=0; else d[i]=MAX;
			while (!q.empty())
			{
				int x=q.front(), o=fir[x], y=e[o].y, dis=MAX; q.pop();
				if (d[x]>dis) break;
				while (o)
				{
					if (!k[y]) dis=d[x]; else if (d[k[y]]==MAX) d[k[y]]=d[x]+2, q.push(k[y]);
					o=e[o].n, y=e[o].y;
				}
			}
			rep(i, 1, n) if (!c[i] && Find(i)) c[i]=true, ans++, can=false;
			if (can) break;
		}
		printf("Scenario #%d:
%d

", tt, ans);
	}
}