poj 2195 java

import java.util.LinkedList;import java.util.Queue;import java.util.Scanner;public class POJ_2195 {static int flow[][];static int cap[][];static int cost[][];static int n ;public static final int MAX = 1000001;static int s,t;public static void main(String[] args) {Scanner scan = new Scanner(System.in);while(true){int r = scan.nextInt();int c = scan.nextInt();if(r==0&&c==0)break;char map[][] = new char[r][c];n = 0;for(int i=0;i<r;i++){map[i] = scan.next().toCharArray();for(int j=0;j<c;j++){if(map[i][j]=='H'){n++;}}}N h[] = new N[n];N m[] = new N[n];int hNum = 0;int mNum = 0;for(int i=0;i<r;i++){for(int j=0;j<c;j++){if(map[i][j] == 'H')h[hNum++] = new N(i,j);if(map[i][j] == 'm')m[mNum++] = new N(i,j);}}    cost = new int[2*n+2][2*n+2];cap = new int[2*n+2][2*n+2];flow = new int[2*n+2][2*n+2];        s = 0;t = 2*n+1;for(int i=1;i<=n;i++){cap[s][i] = 1;cap[i+n][t] = 1;}for(int i=0;i<n;i++){for(int j=0;j<n;j++){cap[i+1][j+n+1] = 1;cost[i+1][j+n+1] = Math.abs(m[i].x-h[j].x)+Math.abs(m[i].y-h[j].y);cost[j+n+1][i+1] = -cost[i+1][j+n+1];}}minCost();int minCostFlow = 0;for(int i=1;i<=n;i++){for(int j=n+1;j<=2*n;j++)minCostFlow += cost[i][j]*flow[i][j];}System.out.println(minCostFlow);}}public static void minCost() {int dist[] = new int[2*n+2];int pre[] = new int[2*n+2];boolean visit[] = new boolean[2*n+2];Queue<Integer> q = new LinkedList<Integer>();while(true){java.util.Arrays.fill(dist, MAX);java.util.Arrays.fill(pre, -1);java.util.Arrays.fill(visit, false);q.add(s);visit[s] = true;dist[s] = 0;while(!q.isEmpty()){int v = q.poll();visit[v] = false;for(int i=1;i<2*n+2;i++){if(flow[v][i]<cap[v][i]&&dist[i]>dist[v]+cost[v][i]){dist[i] = dist[v] + cost[v][i];pre[i] = v;if(!visit[i]){q.add(i);visit[i] = true;}}}}if(pre[t]==-1)break;int minFlow = MAX;for(int u=t;pre[u]!=-1;u=pre[u])minFlow = Math.min(minFlow, cap[pre[u]][u]-flow[pre[u]][u]);for(int u=t;pre[u]!=-1;u=pre[u]){flow[pre[u]][u] += minFlow;flow[u][pre[u]] -= minFlow;}}}}class N{int x;int y;public N(int x, int y) {super();this.x = x;this.y = y;}}