SPFA最短路Java模板

SPFA最短路Java模板

import java.util.LinkedList;
import java.util.Queue;

public class Main {
	
	public static void main(String[] args) {
		
	}
	
	static int MAXN = 10000 + 10;
	static int[] head = new int[MAXN];
	static int[] nxt = new int[MAXN << 1];
	static Node[] edge = new Node[MAXN << 1];
	static boolean[] vis = new boolean[MAXN];
	static int[] dis = new int[MAXN];
	static int INF = 0x3f3f3f3f;
	static int n, tot = 1;
	
	static void add(int x, int y, int cost) {
		edge[tot] = new Node(x, y, cost);
		nxt[tot] = head[x];
		head[x] = tot ++;
	}
	
	static void spfa(int x) {
		for(int i = 1; i <= n; i ++) {
			dis[i] = INF;
			vis[i] = false;
		}
		Queue<Integer> q = new LinkedList<Integer>();
		dis[x] = 0;
		vis[x] = true;
		q.offer(x);
		while(!q.isEmpty()) {
			int u = q.poll();
			vis[u] = false;
			for(int i = head[u]; i > 0; i = nxt[i]) {
				int v = edge[i].y;
				if(dis[v] > dis[u] + edge[i].cost) {
					dis[v] = dis[u] + edge[i].cost;
					if(!vis[v]) {
						vis[v] = true;
						q.offer(v);
					}
				}
			}
		}
	}
	
	static class Node {
		int x, y, cost;
		public Node(int x, int y, int cost) {
			this.x = x;
			this.y = y;
			this.cost = cost;
		}
	}

}