2017滴滴校园招聘笔试题

/**
 * 题目大意:n*m格迷宫,1代表青蛙可以通过,0不能通过
 * 青蛙体力值P,每次走一步,横向走消耗体力值1,向下走不消耗体力,
 * 向上走消耗体力值3.
 * 青蛙初始位置(0,0),迷宫出口(0,m-1)
 * 求青蛙走出迷宫的路径
 */

import java.util.*;

public class Main {

    static class Node {
        int x;
        int y;
        int p;

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

    static int[][] dir = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
    static int[] cost = {3,0,1,1};
    static List<Node> path;

    public static void main(String[] arg) {
        Scanner scan = new Scanner(System.in);
        while (scan.hasNext()) {
            path = new ArrayList<>();
            int n = scan.nextInt();
            int m = scan.nextInt();
            int p = scan.nextInt();
            int[][] matrix = new int[n][m];
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    matrix[i][j] = scan.nextInt();
                }
            }
            boolean[][] isVisited = new boolean[n][m];
            isVisited[0][0] = true;
            path.add(new Node(0,0,p));
            boolean hasPath = dfs(matrix,isVisited,0,0,p);
            if (!hasPath) {
                System.out.println("Can not escape!");
            }else {
                int size = path.size() - 1;
                Node node;
                for (int i = 0; i < size; i++) {
                    node = path.get(i);
                    System.out.print("[" + node.x + "," +node.y +"],");
                }
                node = path.get(size);
                System.out.println("[" + node.x + "," +node.y +"]");
            }

        }
        scan.close();
    }

    private static boolean dfs(int[][] matrix,boolean[][] isVisited,
                            int x, int y, int p) {
        int n = matrix.length;
        int m = matrix[0].length;
        if (p <= 0 && x != 0 && y != m - 1) {
            return false;
        }
        if (x == 0 && y == m - 1 && p >= 0) {
            return true;
        }
        for (int i = 0; i < 4; i++) {
            int nx = x + dir[i][0];
            int ny = y + dir[i][1];
            if (!isInside(n,m,nx,ny)) {
                continue;
            }
            if (matrix[nx][ny] == 1 && !isVisited[nx][ny]) {
                isVisited[nx][ny] = true;
               // System.out.println("push nx="+nx+" ny="+ny+" p="+(p-cost[i]));
                Node node = new Node(nx,ny,p-cost[i]);
                path.add(node);
                if (dfs(matrix,isVisited,nx,ny,p-cost[i])){
                    return true;
                }
                isVisited[nx][ny] = false;
               // System.out.println("pop nx="+nx+" ny="+ny+" p="+(p-cost[i]));
                path.remove(node);
            }

        }
        return false;
    }

    private static boolean isInside(int n,int m,int x,int y) {
        return x >= 0 && x < n && y >= 0 && y < m;
    }
}