学步园

大意略。

二分图最佳匹配，KM算法。

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>
#include <cstring>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <map>
using namespace std;

const int maxn = 110;
const int INF = 0x3f3f3f3f;
const double eps = 1e-7;

struct node
{
	double x, y;
	
	node(double x=0, double y=0): x(x), y(y) {}
}A[maxn], B[maxn];

double sqr(double x) { return x*x; }
double dcmp(double x) { if(fabs(x) < eps) return 0; else return x < 0? -1:1; }
double Dist(node a, node b) { return sqrt(sqr(a.x-b.x) + sqr(a.y-b.y)); }

int n;

double W[maxn][maxn];
double Lx[maxn], Ly[maxn];

int Left[maxn];
bool S[maxn], T[maxn];

bool match(int i)
{
	S[i] = 1;
	for(int j = 1; j <= n; j++) if(!dcmp(Lx[i]+Ly[j]-W[i][j])&& !T[j])
	{
		T[j] = 1;
		if(!Left[j] || match(Left[j]))
		{
			Left[j] = i;
			return 1;
		}
	}
	return 0;
}

void update()
{
	double a = INF;
	for(int i = 1; i <= n; i++) if(S[i])
	for(int j = 1; j <= n; j++) if(!T[j])
		a = min(a, Lx[i]+Ly[j]-W[i][j]);
		
	for(int i = 1; i <= n; i++)
	{
		if(S[i]) Lx[i] -= a;
		if(T[i]) Ly[i] += a;
	}
}

void KM()
{
	for(int i = 1; i <= n; i++)
	{
		Left[i] = Lx[i] = Ly[i] = 0;
		for(int j = 1; j <= n; j++)
			Lx[i] = max(Lx[i], W[i][j]);
	}
	for(int i = 1; i <= n; i++)
	{
		for(;;)
		{
			for(int j = 1; j <= n; j++) S[j] = T[j] = 0;
			if(match(i)) break; else update();
		}
	}
}

void read_case()
{
	for(int i = 1; i <= n; i++)
	{
		double x, y;
		scanf("%lf%lf", &x, &y);
		A[i] = node(x, y);
	}
	for(int i = 1; i <= n; i++)
	{
		double x, y;
		scanf("%lf%lf", &x, &y);
		B[i] = node(x, y);
	}
}

void build()
{
	for(int i = 1; i <= n; i++)
	for(int j = 1; j <= n; j++)
	{
		W[j][i] = -Dist(A[i], B[j]);
	}
}

void solve()
{
	read_case();
	build();
	
	KM();
	
	for(int i = 1; i <= n; i++) printf("%d\n", Left[i]);
}

int main()
{
	int times = 0;
	while(~scanf("%d", &n))
	{
		if(++times > 1) printf("\n");
		solve();
	}
	return 0;
}