KM algorithm - weighted bipartite graph best match

KM algorithm is quite difficult to understand, that it is silent on the "top standard", there are a bunch Theorem (that do not want to see) -
but the code is still relatively good writing,
it is based on a bipartite graph maximum matching algorithm Hungary.
Look at this idea of God rush of blog it! -> | portal | <-
code optimized:
The time complexity of O (n ^ 3)
attached Code

#include <cstdio>  
#include <cstring>
#include <vector>  
#include <algorithm>  
using namespace std;  
const int inf=0x7fffffff,maxn=1010;
int w[maxn][maxn],link[maxn],lx[maxn],ly[maxn],slack[maxn];
bool visy[maxn],visx[maxn];

bool dfs(int node){
    visx[node]=1;
    For(i,1,m){
        if(visy[i]) continue;
        int ls=lx[node]+ly[i]-w[node][i];
        if(ls==0){
            visy[i]=1;
            if(link[i]==-1 || dfs(link[i])){
                link[i]=node;
                return 1;
            }
        }
        if(ls<slack[i])
            slack[i]=ls;
    }
    return 0;
}

int km(){
    int sum=0;
    ak(ly);
    For(i,1,n){
        lx[i]=-inf;
        For(j,1,n){
            if(lx[i]<w[i][j])
                lx[i]=w[i][j];
        }
    }
    memset(link,-1,sizeof(link));
    For(i,1,n){
        For(j,1,m) slack[j]=inf;
        while(1){
            ak(visx),ak(visy);
            if(dfs(i)) break;
            int d=inf;
            For(j,1,m){
                if(!visy[j] && slack[j]<d)
                    d=slack[j];
            }
            For(j,1,n)
                if(visx[j])
                    lx[j]-=d;
            For(j,1,m)
                if(visy[j])
                    ly[j]+=d;
                else slack[j]-=d;
        }
    }
    For(i,1,m){
        if(link[i]>-1){
            sum+=w[link[i]][i];
        }
    }
    return sum;
}

The above blog wrote these details are resolved, not repeat them here.