本题关键字

two pointers

题目描述

https://leetcode.com/problems/squares-of-a-sorted-array/

Given an array of integers A sorted in non-decreasing order, return an array of the squares of each number, also in sorted non-decreasing order.

 

Example 1:

Input: [-4,-1,0,3,10]
Output: [0,1,9,16,100]
Example 2:

Input: [-7,-3,2,3,11]
Output: [4,9,9,49,121]
 

Note:

1 <= A.length <= 10000
-10000 <= A[i] <= 10000
A is sorted in non-decreasing order.

博主提交的代码

垃圾，一坨屎

public int[] sortedSquares(int[] A) {
        int[] clone = A.clone();
        for( int i = 0; i < clone.length;i++){
            clone[i] = clone[i] * clone[i];
        }
        Arrays.sort(clone);
        return clone;
        
    }

别人优秀的代码

https://leetcode.com/problems/squares-of-a-sorted-array/discuss/221922/Java-two-pointers-O(N)

class Solution {
    public int[] sortedSquares(int[] A) {
        int n = A.length;
        int[] result = new int[n];
        int i = 0, j = n - 1;
        for (int p = n - 1; p >= 0; p--) {
            if (Math.abs(A[i]) > Math.abs(A[j])) {
                result[p] = A[i] * A[i];
                i++;
            } else {
                result[p] = A[j] * A[j];
                j--;
            }
        }
        return result;
    }
}