二分图最大匹配(匈牙利算法) UVA 10080 Gopher II

题目传送门

/*
    匈牙利算法：这题比UVA_670简单，注意是要被吃的鼠的最少个数，套模板
*/
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <vector>
using namespace std;

const int MAXN = 1e2 + 10;
const int INF = 0x3f3f3f3f;
struct P
{
    double x, y;
}a[MAXN], b[MAXN];
bool vis[MAXN];
int lk[MAXN];
vector<int> G[MAXN];

double get_dis(double x1, double y1, double x2, double y2)
{
    return sqrt ((x1-x2) * (x1-x2) + (y1-y2) * (y1-y2));
}

bool DFS(int u)
{
    for (int i=0; i<G[u].size (); ++i)
    {
        int v = G[u][i];
        if (!vis[v])
        {
            vis[v] = true;
            if (lk[v] == -1 || DFS (lk[v]))
            {
                lk[v] = u;    return true;
            }
        }
    }

    return false;
}

int hungary(int n)
{
    int res = 0;    memset (lk, -1, sizeof (lk));
    for (int i=1; i<=n; ++i)
    {
        memset (vis, false, sizeof (vis));
        if (DFS (i))    res++;
    }

    return res;
}

int main(void)        //UVA 10080 Gopher II
{
//    freopen ("UVA_10080.in", "r", stdin);

    int n, m, s, v;
    while (scanf ("%d%d%d%d", &n, &m, &s, &v) == 4)
    {
        for (int i=1; i<=n; ++i)    scanf ("%lf%lf", &a[i].x, &a[i].y);
        for (int i=1; i<=m; ++i)    scanf ("%lf%lf", &b[i].x, &b[i].y);
        for (int i=1; i<=n; ++i)    G[i].clear ();
        for (int i=1; i<=n; ++i)
        {
            for (int j=1; j<=m; ++j)
            {
                if (get_dis (a[i].x, a[i].y, b[j].x, b[j].y) <= s * v)    G[i].push_back (j);
            }
        }

        printf ("%d
", n - hungary (n));
    }

    return 0;
}