HDU 2255 奔小康赚大钱

#include <bits/stdc++.h>
using namespace std;

const int inf = 0x3f3f3f3f;
const int maxn = 550;
int N;
int mp[maxn][maxn];
int exg[maxn], exb[maxn];
int visg[maxn], visb[maxn];
int match[maxn], slack[maxn];

bool dfs(int u) {
    visg[u] = 1;
    for(int v = 0; v < N; v ++) {
        if(visb[v]) continue;
        int gap = exg[u] + exb[v] - mp[u][v];

        if(!gap) {
            visb[v] = 1;
            if(match[v] == -1 || dfs(match[v])) {
                match[v] = u;
                return true;
            }
        } else slack[v] = min(slack[v], gap);
    }
    return false;
}

int KM() {
    memset(match, -1, sizeof(match));
    memset(exb, 0, sizeof(exb));

    for(int i = 0; i < N; i ++) {
        exg[i] = mp[i][0];
        for(int j = 1; j < N; j ++)
            exg[i] = max(exg[i], mp[i][j]);
    }
    for(int i = 0; i < N; i ++) {
        memset(slack, inf, sizeof(slack));
        while(1) {
            memset(visg, 0, sizeof(visg));
            memset(visb, 0, sizeof(visb));

            if(dfs(i)) break;

            int d = inf;
            for(int j = 0; j < N; j ++)
                if(!visb[j]) d = min(d, slack[j]);

            for(int j = 0; j < N; j ++) {
                if(visg[j]) exg[j] -= d;
                if(visb[j]) exb[j] += d;
                else slack[j] -= d;
            }
        }
    }
    int res = 0;
    for(int i = 0; i < N; i ++)
        res += mp[match[i]][i];
    return res;
}

int main() {
    while(~scanf("%d", &N)) {
        for(int i = 0; i < N; i ++) {
            for(int j = 0; j < N; j ++)
                scanf("%d", &mp[i][j]);
        }
        printf("%d\n", KM());
    }

    return 0;
}