[HDU 2255] 奔小康赚大钱

[题目链接]

          http://acm.hdu.edu.cn/showproblem.php?pid=2255

[算法]

          KM算法模板题

[代码]

        

#include<bits/stdc++.h>
using namespace std;
#define MAXN 510
const int INF = INT_MAX;

int n,i,j,delta;
int la[MAXN],lb[MAXN],match[MAXN];
int w[MAXN][MAXN];
bool visiteda[MAXN],visitedb[MAXN];

inline bool dfs(int u)
{
        int v;
        visiteda[u] = true;
        for (v = 1; v <= n; v++)
        {
                if (!visitedb[v])
                {
                        if (la[u] + lb[v] == w[u][v])
                        {
                                visitedb[v] = true;
                                if (!match[v] || dfs(match[v]))
                                {
                                        match[v] = u;
                                        return true;
                                }
                        } else delta = min(delta,la[u] + lb[v] - w[u][v]);
                } 
        }
        return false;
}
inline int KM()
{
        int i,j,ret;
        memset(match,0,sizeof(match));
        for (i = 1; i <= n; i++) 
        {
                la[i] = -INF;
                lb[i] = 0;
                for (j = 1; j <= n; j++) la[i] = max(la[i],w[i][j]);
        }
        for (i = 1; i <= n; i++)
        {
                while (true)
                {
                        delta = INF;
                        for (j = 1; j <= n; j++) visiteda[j] = visitedb[j] = false;
                        if (dfs(i)) break;
                        for (j = 1; j <= n; j++)
                        {
                                if (visiteda[j]) la[j] -= delta;
                                if (visitedb[j]) lb[j] += delta;
                        }
                }
        }
        ret = 0;
        for (i = 1; i <= n; i++) ret += w[match[i]][i];
        return ret;
}

int main() 
{    
        while (scanf("%d",&n) != EOF)
        {
                for (i = 1; i <= n; i++) 
                {
                        for (j = 1; j <= n; j++)
                        {
                                scanf("%d",&w[i][j]);    
                        }    
                }        
                printf("%d
",KM());
        }
        
        return 0;
    
}