KM算法

#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <iostream>
using namespace std;
/*  KM算法
*   复杂度O(nx*nx*ny)
*  求最大权匹配
*   若求最小权匹配，可将权值取相反数，结果取相反数
*  点的编号从0开始
*/
const int N = 310;
const int INF = 0x3f3f3f3f;
int nx,ny;//两边的点数
int g

;//二分图描述
int match
,lx
,ly
;//y中各点匹配状态，x,y中的点标号
int slack
;
bool visx
,visy
;
bool DFS(int x)
{
visx[x] = true;
for(int y = 0; y < ny; y++)
{
if(visy[y])continue;
int tmp = lx[x] + ly[y] - g[x][y];
if(tmp == 0)
{
visy[y] = true;
if(match[y] == -1 || DFS(match[y]))
{
match[y] = x;
return true;
}
}
else if(slack[y] > tmp)
slack[y] = tmp;
}
return false;
}
int KM()
{
memset(match,-1,sizeof(match));
memset(ly,0,sizeof(ly));
for(int i = 0;i < nx;i++)
{
lx[i] = -INF;
for(int j = 0;j < ny;j++)
if(g[i][j] > lx[i])
lx[i] = g[i][j];
}
for(int x = 0;x < nx;x++)
{
for(int i = 0;i < ny;i++)
slack[i] = INF;
while(true)
{
memset(visx,false,sizeof(visx));
memset(visy,false,sizeof(visy));
if(DFS(x))break;
int d = INF;
for(int i = 0;i < ny;i++)
if(!visy[i] && d > slack[i])
d = slack[i];
for(int i = 0;i < nx;i++)
if(visx[i])
lx[i] -= d;
for(int i = 0;i < ny;i++)
{
if(visy[i])ly[i] += d;
else slack[i] -= d;
}
}
}
int res = 0;
for(int i = 0;i < ny;i++)
if(match[i] != -1)
res += g[match[i]][i];
return res;
}