hdu 2255 奔小康赚大钱 KM模板题目

http://acm.hdu.edu.cn/showproblem.php?pid=2255

O(n^4)模板

#include <cstdio>
#include <cstring>
#include <iostream>
#define maxn 301
using namespace std;

const int inf = 99999999;
int w[maxn][maxn],link[maxn];
int lx[maxn],ly[maxn];
bool vtx[maxn],vty[maxn];
int nx,ny;

bool dfs(int i)
{
    int j;
    vtx[i] = true;
    for (j = 0; j < ny; ++j)
    {
        if (!vty[j] && lx[i] + ly[j] == w[i][j])
        {
            vty[j] = true;
            if (link[j] == -1 || dfs(link[j]))
            {
                link[j] = i;
                return true;
            }
        }
    }
    return false;
}
int KM()
{
    int i,j,k;
    for (i = 0; i < nx; ++i)
    {
        for (j = 0,lx[i] = -inf; j < ny; ++j)
        {
            lx[i] = max(lx[i],w[i][j]);
        }
    }
    for (i = 0; i < maxn; ++i)
    {
        link[i] = -1; ly[i] = 0;
    }
    for (i = 0; i < nx; ++i)
    {
        while (1)
        {
            for (j = 0; j < maxn; ++j) vtx[j] = vty[j] = false;
            if (dfs(i)) break;
            int d = inf;
            for (j = 0; j < nx; ++j)
            {
                if (vtx[j])
                {
                    for (k = 0; k < ny; ++k)
                    {
                        if (!vty[k]) d = min(d,lx[j] + ly[k] - w[j][k]);
                    }
                }
            }
            if (d == inf) return -1;
            for (j = 0; j < nx; ++j) if (vtx[j]) lx[j] -= d;
            for (j = 0; j < ny; ++j) if (vty[j]) ly[j] += d;
        }
    }
    int sum = 0;
    for (i = 0; i < ny; ++i)
    if (link[i] > -1) sum += w[link[i]][i];
    return sum;
}
int main()
{
    int i,j;
    while (~scanf("%d",&nx))
    {
        ny = nx;
        memset(w,0,sizeof(w));
        for (i = 0; i < nx; ++i)
        {
            for (j = 0; j < ny; ++j)
            {
                scanf("%d",&w[i][j]);
            }
        }
        printf("%d\n",KM());
    }
    return 0;
}