zoukankan      html  css  js  c++  java
  • LC 969. Pancake Sorting

    Given an array A, we can perform a pancake flip: We choose some positive integer k <= A.length, then reverse the order of the first k elements of A.  We want to perform zero or more pancake flips (doing them one after another in succession) to sort the array A.

    Return the k-values corresponding to a sequence of pancake flips that sort A.  Any valid answer that sorts the array within 10 * A.length flips will be judged as correct.

    Example 1:

    Input: [3,2,4,1]
    Output: [4,2,4,3]
    Explanation: 
    We perform 4 pancake flips, with k values 4, 2, 4, and 3.
    Starting state: A = [3, 2, 4, 1]
    After 1st flip (k=4): A = [1, 4, 2, 3]
    After 2nd flip (k=2): A = [4, 1, 2, 3]
    After 3rd flip (k=4): A = [3, 2, 1, 4]
    After 4th flip (k=3): A = [1, 2, 3, 4], which is sorted. 
    

    Example 2:

    Input: [1,2,3]
    Output: []
    Explanation: The input is already sorted, so there is no need to flip anything.
    Note that other answers, such as [3, 3], would also be accepted.
    

    Note:

    1. 1 <= A.length <= 100
    2. A[i] is a permutation of [1, 2, ..., A.length]

    Runtime: 14 ms

    class Solution {
      static public List<Integer> pancakeSort(int[] A) {
        List<Integer> ret = new ArrayList<>();
        for(int x = A.length,i=0; x>= 1; x--){
          //System.out.print(x);
          for(i=0; A[i] != x; i++);
          reverse(A, i);
          ret.add(i+1);
          reverse(A, x-1);
          ret.add(x);
        }
        return ret;
      }
      static void reverse(int[] A, int pos){
        for(int i=0,j=pos; i<j; i++,j--){
          int tmp = A[i];
          A[i] = A[j];
          A[j] = tmp;
        }
      }
    }
  • 相关阅读:
    解决vue项目中出现Invalid Host header问题
    vue、uni-app常用的过滤器
    vue让子组件刷新的方法
    工作中 交换机 相关
    XOR Sum in Assembly
    mysql 秒转化为-时分秒
    springboot项目-声明式事务失效
    DOM 元素 classList 的操作方式
    normalize() 和 splitText()
    js 一道面试题,有关函数执行逻辑
  • 原文地址:https://www.cnblogs.com/ethanhong/p/10255031.html
Copyright © 2011-2022 走看看