#include <iostream>

#include<cstring>

#include<cstdio>

#include<cmath>

const int maxn = 301;

const int INF = (1<<31)-1;

int w[maxn][maxn];

int lx[maxn],ly[maxn]; //顶标

int linky[maxn];

int visx[maxn],visy[maxn];

int slack[maxn];

int n;

bool find(int x)

{

    visx[x] = true;

    for(int y = 1; y <=n; 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 = 1; i <=n; i++)			//初始化顶标

    {

         lx[i] = -INF;

         for(j = 1; j <=n; j++)

         {

            if(w[i][j] > lx[i])   lx[i] = w[i][j];

         }

    }

    for(int x = 1; x <=n; x++)

    {

        for(i = 1; i <=n; 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 = 1; i <=n; i++)

            {

                if(!visy[i] && d > slack[i])    d = slack[i];

            }

            for(i = 1; i <=n; i++)

            {

                if(visx[i])    lx[i] -= d;

            }

            for(i = 1; i <=n; i++)

            {

                if(visy[i])	   ly[i] += d;

                else           slack[i] -= d;

            }

        }

    }

    int result = 0;

    for(i = 1; i <=n; i++)

    {

	    if(linky[i]>-1)

	    {

	        result += w[linky[i]][i];

	    }

    }

    return result;

}

int main()

{

    while(scanf("%d",&n)==1)

    {

        int cost;

        for(int i=1;i<=n;i++)

        {

	        for(int j=1;j<=n;j++)

	        {

	            scanf("%d",&cost);

	            w[i][j] = cost;

	        }

        }

        printf("%d\n",KM());

    }

    return 0;

}

更新顶标的问题的了