【Java模板】Djkstra模板

基于邻接表（链表形式）实现。

import java.util.*;

public class Dijkstra模板 {
	static int dis[] = new int[1005];
	static boolean vis[] = new boolean[1005];
	static int head[] = new int[1005]; // 存放链头
	static edge[] e = new edge[1005];
	static int len; // 边的个数
	static int n, m; // n 顶点个数 m 边数

	static void init() {
		Arrays.fill(head, -1);
		Arrays.fill(dis, 0x3f3f3f3f); // 赋值为负无穷
	}

	static void add(int u, int v, int w) {
		e[len] = new edge(v, w, head[u]); // 前插法
		head[u] = len++; // 将u指向新添加的边
	}

	// 无向边的添加
	static void add2(int u, int v, int w) {
		add(u, v, w);
		add(v, u, w);
	}

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		init();
		n = sc.nextInt();
		m = sc.nextInt();
		int u, v, w;
		for (int i = 0; i < m; i++) {
			u = sc.nextInt();
			v = sc.nextInt();
			w = sc.nextInt();
			add2(u, v, w);
		}
		dijkstra1(1);
		for (int i = 1; i <= n; i++) {
			System.out.print(dis[i] + " ");
		}
		System.out.println();
		System.out.println(dis[n]);
	}

	/*
	 * 利用优先级队列进行优化 O(vlgv + e)
	 */
	static void dijkstra1(int u) {
		dis[u] = 0;
		PriorityQueue<node> q = new PriorityQueue<node>();
		q.add(new node(0, u));

		while (!q.isEmpty()) {
			u = q.poll().v;
			//因为可能有重复点进去
			if (vis[u]) continue;
			vis[u] = true;
			
			for (int j = head[u]; j != -1; j = e[j].next) {
				int v = e[j].v;
				int w = e[j].w;
				if (!vis[v] && dis[v] > dis[u] + w) {
					dis[v] = dis[u] + w;
					q.add(new node(dis[v], v));
				}
			}
		}
	}

	/*
	 * 不优化
	 */
	static void dijkstra2(int u) {
		dis[u] = 0;
		for (int i = 0; i < n; i++) { // 循环n遍 标记n个点
			int mind = 1000000000, minj = -1;
			for (int j = 1; j <= n; j++) { // 从n个点中找出dis最小的
				if (!vis[j] && dis[j] < mind) {
					mind = dis[j];
					minj = j;
				}
			}

			if (minj == -1) {
				// 代表有点无法到达
				return;
			}
			vis[minj] = true; // 将这个最小的点进行标记
			for (int j = head[minj]; j != -1; j = e[j].next) {
				int v = e[j].v;
				int w = e[j].w;
				if (!vis[v] && dis[v] > dis[minj] + w) {
					dis[v] = dis[minj] + w;
				}
			}
		}
	}
}

class edge {
	int v, w, next;

	public edge(int v, int w, int next) {
		this.v = v;
		this.w = w;
		this.next = next;
	}

	public edge() {
	}
}

class node implements Comparable<node> {
	int minDis, v;

	public node(int minDis, int v) {
		this.minDis = minDis;
		this.v = v;
	}

	public int compareTo(node o) {
		if (minDis == o.minDis) {
			return (v - o.v); // 优先队列中 小的在头
		}
		return  (minDis - o.minDis);
	}
}

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来源： https://blog.csdn.net/qq_41280600/article/details/97373438