HDU 2255 奔小康赚大钱

KM算法  二分图最大权值匹配

#include <iostream>
#include<cstring>
#include<cstdio>
#include<cmath>

const int maxn = 356;
const int INF = (1<<31)-1;
int w[maxn][maxn];
int lx[maxn],ly[maxn]; 
int linky[maxn];
int visx[maxn],visy[maxn];
int slack[maxn];
int nx,ny;
bool find(int x)
{
    visx[x] = true;
    for(int y = 0; y < ny; y++)
    {
        if(visy[y])
            continue;
        int t = lx[x] + ly[y] - w[x][y];
        if(t==0)
        {
            visy[y] = true;
            if(linky[y]==-1 || find(linky[y]))
            {
                linky[y] = x;
                return true;       
            }
        }
        else if(slack[y] > t)
            slack[y] = t;
    }
    return false;            
}

int KM()               
{
    int i,j;

    memset(linky,-1,sizeof(linky));
    memset(ly,0,sizeof(ly));
    for(i = 0; i < nx; i++)
        for(j = 0,lx[i] = -INF; j < ny; j++)
            if(w[i][j] > lx[i])
                lx[i] = w[i][j];
    for(int x = 0; x < nx; x++)
    {
        for(i = 0; i < ny; i++)
            slack[i] = INF;
        while(true)
        {
            memset(visx,0,sizeof(visx));
            memset(visy,0,sizeof(visy));
            if(find(x))                  
                break;
            int d = INF;
            for(i = 0; i < ny; i++)        
            {
                if(!visy[i] && d > slack[i])
                    d = slack[i];
            }
            for(i = 0; i < nx; i++)
            {
                if(visx[i])
                    lx[i] -= d;
            }
            for(i = 0; i < ny; i++)
            {
                if(visy[i])
                     ly[i] += d;
                else
                     slack[i] -= d;
            }
        }
    }
    int result = 0;
    for(i = 0; i < ny; i++)
    if(linky[i]>-1)
        result += w[linky[i]][i];
    return result;
}

int main()
{
    int n;
    while(~scanf("%d",&n))
    {
        nx=ny=n;
        for(int i=0;i<n;i++)
            for(int j=0;j<n;j++)
            {
                int x;
                scanf("%d",&x);
                w[i][j]=x;
            }
        printf("%d
",KM());
    }
    return 0;
}