阿里巴巴2020届实习生面试题（送快递最短路径）

解决方法：使用排列方法，将所有排列搞出来，计算最短路径

import java.util.Scanner;


/**
 * 节点定义
 *
 */
class Point {
  // x坐标点
  int px;
  // y坐标点
  int py;

  public Point(int px, int py) {
    this.px = px;
    this.py = py;

  }

  /**
   * 两个点的距离计算
   * 将所有组合找出来计算最短
   * @param p
   * @return
   */
  public int getLength(Point p) {

    return Math.abs(px - p.px) + Math.abs(py - p.py);

  }

}

/**
 * 主的实现类
 *
 */
class Main {

  static final Point START = new Point(0, 0);

  static int minPath = Integer.MAX_VALUE;

  /**
   * 根据自己的实现想法进行实现，可以新添加子函数等
   * 
   * @param start       开始节点
   * @param points      节点序列
   * @return
   */
  public static int calculateMinPath(Point start, Point[] points) {

    return 0;

  }

  /**
   * 主函数
   * 
   * @param args
   */
  public static void main(String[] args) {     //面试官，答题结束，希望您能看到

    Scanner input = new Scanner(System.in);
    // 输入行数
    int pnum = Integer.parseInt(input.nextLine().trim());

    Point[] points = new Point[pnum];

    for (int i = 0; i < pnum; i++) {

      String[] locations = input.nextLine().trim().split(",");
      // 输入每个点的坐标
      points[i] = new Point(Integer.parseInt(locations[0]),
          Integer.parseInt(locations[1]));
    }
    minPath = a(points,0);  
    System.out.println(minPath);

  }

  public static int a(Point[] points , int n) {
      if(n == points.length) {
          
          int sum = points[0].getLength(START);
          for (int i = 1 ; i<points.length; i++) {
              sum = sum + points[i-1].getLength(points[i]);
             
          }
          sum = sum + points[points.length -1].getLength(START);
          minPath = Math.min(minPath , sum);
          return minPath;
      }
      for (int i = n; i < points.length; i++) {
          swap(points,n,i);
          a(points,n+1);
          swap(points,n,i);
      }
      return minPath;
  }
  
  public static void swap(Point[] points, int i, int j) {
      if (i == j) return;
      Point temp = points[i];
      points[i] = points[j];
      points[j] = temp;
  }

}