poj 2195 Going Home 二分图最小权匹配KM算法

//poj 2195
//sep9
#include <iostream>
using namespace std;
const int maxN=128;
char g[maxN][maxN];
int mx[maxN],my[maxN],hx[maxN],hy[maxN];
int w[maxN][maxN];
int lx[maxN],ly[maxN],linky[maxN];
int visx[maxN],visy[maxN];
int slack[maxN];
int nx,ny;

bool find(int x)
{
	visx[x]=true;
	for(int y=0;y<ny;++y){
		if(visy[y])
			continue;
		int t=lx[x]+ly[y]-w[x][y];
		if(t==0){
			visy[y]=true;
			if(linky[y]==-1||find(linky[y])){
				linky[y]=x;
				return true;
			}
		}
		else if(slack[y]>t)
			slack[y]=t;
	}	
	return false;
}

int KM()
{
	int i,j;
	memset(linky,-1,sizeof(linky));
	memset(ly,0,sizeof(ly));
	for(i=0;i<nx;++i)
		for(j=0,lx[i]=INT_MIN;j<ny;++j)
			if(w[i][j]>lx[i])
				lx[i]=w[i][j];
	for(int x=0;x<nx;++x){
		for(i=0;i<ny;++i)
			slack[i]=INT_MAX;
		while(1){
			memset(visx,0,sizeof(visx));
			memset(visy,0,sizeof(visy));
			if(find(x))
				break;
			int d=INT_MAX;
			for(i=0;i<ny;++i)
				if(!visy[i]&&slack[i]<d)
					d=slack[i]; 
			if(d==INT_MAX)
				return -1;
			for(i=0;i<nx;++i)
				if(visx[i])
					lx[i]-=d;
			for(i=0;i<ny;++i)
				if(visy[i])
					ly[i]+=d;
				else
					slack[i]-=d;
		}
	}
	int result=0;
	for(i=0;i<ny;++i)
		if(linky[i]>-1)
			result+=w[linky[i]][i];
	return result;				
}

int main()
{
	int i,j,n,m;
	while(scanf("%d%d",&n,&m)==2){
		if(n==0&&m==0)
			break;
		for(i=0;i<n;++i)
			scanf("%s",g[i]);
		int mcnt=0,hcnt=0;
		for(i=0;i<n;++i)
			for(j=0;j<m;++j)
				if(g[i][j]=='m'){
					mx[mcnt]=i;
					my[mcnt]=j;
					++mcnt;
				}
				else if(g[i][j]=='H'){
					hx[hcnt]=i;
					hy[hcnt]=j;
					++hcnt;
				}	
		for(i=0;i<mcnt;++i)
			for(j=0;j<hcnt;++j){
				w[i][j]=abs(mx[i]-hx[j])+abs(my[i]-hy[j]);
				w[i][j]=-w[i][j];
			}
		nx=ny=mcnt;
		printf("%d\n",-KM());
	}
	return 0;	
}