HDU2255——二分匹配——奔小康赚大钱

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn = 310;
int n;
int visx[maxn],visy[maxn],Lx[maxn],Ly[maxn],map[maxn][maxn];
int match[maxn];
int find(int u)
{
    visx[u] = 1;
    for(int v = 1; v <= n ; v++){
        if(!visy[v] && Lx[u] + Ly[v] == map[u][v]){
            visy[v] = 1;
            if(match[v] == -1 || find(match[v])){
                match[v] = u;
               return 1;
            }
        }
    }
    return 0;
}
void update()
{
    int a = 1 << 30;
    for(int i = 1; i <= n ;i++)
        if(visx[i])
        for(int j = 1; j <= n ; j++)
            if(!visy[j])
             a = min(a,Lx[i] + Ly[j] - map[i][j]);
    for(int i = 1; i <= n ;i++){
        if(visx[i]) Lx[i] -= a;
        if(visy[i]) Ly[i] += a;
    }
}
void KM()
{
    memset(match,-1,sizeof(match));
    for(int i = 1 ; i <= n ; i++){
        Lx[i] = Ly[i] = 0;
        for(int j = 1; j <= n; j++){
            Lx[i] = max(Lx[i],map[i][j]);
        }
    }
    for(int i = 1; i <= n ;i++){
        for(; ;){
            memset(visx,0,sizeof(visx));
            memset(visy,0,sizeof(visy));
            if(find(i)) break;
            else update();
        }
    }
}
int main()
{
    while(~scanf("%d",&n)){
    for(int i = 1;i <= n ;i++)
        for(int j = 1; j <= n ;j++)
        scanf("%d",&map[i][j]);
    KM();
    int res = 0;
    for(int i = 1; i <= n ; i++){
        if(match[i] != -1){
            res += map[match[i]][i];
        }
    }
    printf("%d\n",res);
    }
    return 0;
}