codevs 1028 花店橱窗布置 KM算法

题目链接

n个花， m个花瓶， 每个花放到一个花瓶里会产生一个值w[i][j], 一个花只能放到一个花瓶里， 一个花瓶只能放一个花， 求产生的最大值。

带权二分图模板。

#include <iostream>
#include <vector>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <string>
#include <queue>
#include <stack>
#include <bitset>
using namespace std;
#define pb(x) push_back(x)
#define ll long long
#define mk(x, y) make_pair(x, y)
#define lson l, m, rt<<1
#define mem(a) memset(a, 0, sizeof(a))
#define rson m+1, r, rt<<1|1
#define mem1(a) memset(a, -1, sizeof(a))
#define mem2(a) memset(a, 0x3f, sizeof(a))
#define rep(i, n, a) for(int i = a; i<n; i++)
#define fi first
#define se second
typedef pair<int, int> pll;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int mod = 1e9+7;
const int inf = 1061109567;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
const int M = 105;
bool sx[M], sy[M];
int match[M], w[M][M], n, m, d, lx[M], ly[M];
void init ()
{
    memset (w, 0, sizeof(w));
}
bool dfs (int u)
{
    int v; sx[u] = true;
    for (v = 0; v < m; v++)
    {
        if (!sy[v] && lx[u]+ly[v]==w[u][v])
        {
            sy[v] = true;
            if (match[v] == -1 || dfs (match[v]))
            {
                match[v] = u;
                return true;
            }
        }
    }
    return false;
}

int KM ()
{
    int i, j, k, sum = 0;
    memset (ly, 0, sizeof(ly));
    for (i = 0; i < n; i++)
    {
        lx[i] = -inf;
        for (j = 0; j < m; j++)
            if (lx[i] < w[i][j])
                lx[i] = w[i][j];
    }
    memset (match, -1, sizeof(match));
    for (i = 0; i < n; i++)
    {
        while (1)
        {
            memset (sx, false, sizeof(sx));
            memset (sy, false, sizeof(sy));
            if (dfs (i))
                break;
            d = inf;
            for (j = 0; j < n; j++)
                if (sx[j])
                    for (k = 0; k < m; k++)
                        if (!sy[k])
                            d = min (d, lx[j]+ly[k]-w[j][k]);
            if (d == inf)
                return -1;
            for (j = 0; j < n; j++)
                if (sx[j])
                    lx[j] -= d;
            for (j = 0; j < m; j++)
                if (sy[j])
                    ly[j] += d;
        }
    }
    for (i = 0; i < m; i++)
        if (match[i] > -1)
            sum += w[match[i]][i];
    return sum;
}
int main()
{
    cin>>n>>m;
    for(int i = 0; i<n; i++) {
        for(int j = 0; j<m; j++) {
            scanf("%d", &w[i][j]);
        }
    }
    int ans = KM();
    cout<<ans<<endl;
    return 0;
}