本文共 1675 字，大约阅读时间需要 5 分钟。

注意 变量的范围 要取long类型

package csp2014_9_4;import java.util.Arrays;import java.util.LinkedList;import java.util.List;import java.util.Scanner;import org.w3c.dom.css.ViewCSS;public class Main {	long[][]map;	boolean [][]visit;	int n, m, k, d;	int [][]dir = {
  {0,1},{0,-1},{1,0},{-1,0}};	long ans;	LinkedList
   
     que;	public static void main(String[] args) {		new Main().run();	}	public void run() {		Scanner in = new Scanner(System.in);		while(in.hasNext()) {			n = in.nextInt();			m = in.nextInt();			k = in.nextInt();			d = in.nextInt();			que = new LinkedList<>();			visit = new boolean[n+1][n+1];			map = new long[n+1][n+1];			for(int i = 0; i < m; i++ ) {				int x = in.nextInt();				int y = in.nextInt();				que.offer(new Node(x, y, 0));			}						for(int i = 0; i < k; i++ ) {				int x = in.nextInt();				int y = in.nextInt();				long num = in.nextInt();				map[x][y] = num; 			}			for(int i = 0; i < d; i++ ) {				int x = in.nextInt();				int y = in.nextInt();				visit[x][y] = true;			}			ans = 0;			bfs();				System.out.println(ans);		}			}		public void bfs() {		int cnt = 0;		while(!que.isEmpty()) {			Node node = que.poll();			for(int i = 0; i < 4; i++ ) {				int xx = node.x + dir[i][0];				int yy = node.y + dir[i][1];				if(xx>0&&yy>0&&xx<=n&&yy<=n&&!visit[xx][yy]) {					visit[xx][yy] = true;					ans += (node.step+1)*map[xx][yy];					Node tmp = new Node(xx, yy, node.step+1);					que.offer(tmp);				}			}		}	}}class Node{	int x, y;	long mum;	long step;	public Node(int x, int y, long s) {		step = s;		this.x = x;		this.y = y;	}	}
   

上面 可以在达到目标后提前终止

if(map[xx][yy] != 0) {						ans += (node.step+1)*map[xx][yy];						cnt++;						if(cnt == k)							return;					}

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