BFS demo

Main.java

import java.util.LinkedList;

public class Main {

    public static void main(String[] args) {
        
    }

    boolean bfs(Node start, Node end) {
        LinkedList<Node> queue = new LinkedList<>();
        Node vn; // 队列下一个节点
        Node vw; // 相邻节点

        int len = end.x - start.x + 1;
        boolean[][] visit = new boolean[len][len];
        int[][] dir = new int[][]{
                {-1, 0}, {1, 0}, {0, -1}, {0, 1} // 上下左右
        };

        queue.push(start);
        visit[start.x][start.y] = true;

        while (!queue.isEmpty()) {
            vn = queue.pop();
            for (int i = 0; i < len; i++) {
                vw = new Node(vn.x + dir[i][0], vn.y + dir[i][1], len);
                if (!vw.isValid()) {
                    continue;
                }
                if (vw.equals(end)) {
                    return true; // 找到终点，返回
                }
                if (!visit[vw.x][vw.y]) {
                    visit[vw.x][vw.y] = true;
                }
            }
        }
        return false;
    }

    class Node {

        int x, y, len;

        Node(int x, int y, int len) {
            this.x = x;
            this.y = y;
            this.len = len;
        }

        boolean equals(Node node) {
            return this.x == node.x && this.y == node.y;
        }

        boolean isValid() {
            return x < len && x >= 0 &&
                    y < len && y >= 0;
        }
    }
}