HDU 2255(KM模板）

带权二分图最大权值匹配问题

关于KM算法的讲述可以看下面这篇博客（转） ：
https://blog.csdn.net/chenshibo17/article/details/79933191

下面是自用KM模板 ：
其中的 n 是二分图中左侧个数, m 是二分图中右侧个数， 因为此题左侧和右侧个数相同， 此时 n 和 m 相同。

ps：还是不知道为什么从 1 ~ n（而不是从 0 ~ n-1）做操作就会tle，相关的范围全都改过了，干脆以后都从 0 开始记吧。

#include <stdio.h>
#include <vector>
#include <algorithm>
#include <string.h>
#include <limits.h>
#include <string>
#include <iostream>
#include <queue>
#include <math.h>
#include <map>
#include <stack>
#include <set>
#define ms(x, n) memset(x,n,sizeof(x));
#define forn(i, n) for(int i = 0; i < (int)n; i++)
#define For(i, a, b) for(int i = (a); i <= (int)(b); i++)
#define INF 0x3f3f3f3f
#define PI acos(-1.0)
#define mod(x) (x % 10000007)
typedef long long int ll;
typedef unsigned long long int ull;
using namespace std;

#define maxn 305
int n , m, con[maxn][maxn], num_a[maxn], num_b[maxn], match[maxn], slack[maxn], book_a[maxn], book_b[maxn];

bool dfs(int x)
{
    book_a[x] = 1;
    for (int i = 0; i < m; ++i) {
        if (book_b[i]) continue;
        int gap = num_a[x] + num_b[i] - con[x][i];
        if (!gap) {
            book_b[i] = 1;
            if (match[i] == -1 || dfs(match[i])) {
                match[i] = x;
                return true;
            }
        } else {
            slack[i] = min(slack[i], gap);
        }
    }
    return false;
}

int KM()
{
    ms(match, -1); ms(num_b, 0);
    for (int i = 0; i < n; ++i) {
        num_a[i] = con[i][0];
        for (int j = 1; j < m; ++j) {
            num_a[i] = max(num_a[i], con[i][j]);
        }
    }

    for (int i = 0; i < n; ++i) {
        fill(slack, slack + n, INF);
        while (1) {
            ms(book_a, 0); ms(book_b, 0);

            if (dfs(i)) break;
            int d = INF;
            for (int j = 0; j < m; ++j)
                if (!book_b[j]) d = min(d, slack[j]);

            for (int j = 0; j < n; ++j) {
                if (book_a[j]) num_a[j] -= d;
            }
            for (int j = 0; j < m; ++j) {
                if (book_b[j]) num_b[j] += d;
                else slack[j] -= d;
            }
        }
    }
    int res = 0;
    for (int i = 0; i < m; ++i) res += con[match[i]][i];
    return res;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    while (cin >> n) {
        m = n;
        for (int i = 0; i < n; ++i)
            for (int j = 0; j < m; ++j)
                cin >> con[i][j];

        int ans = KM();
        printf("%d\n", ans);
    }
    return 0;
}