905. Sort Array By Parity.md

905. Sort Array By Parity

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leetcode Daily Challenge on August 21th, 2020.

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Difficulty : Easy

Related Topics : Array

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Given an array A of non-negative integers, return an array consisting of all the even elements of A, followed by all the odd elements of A.

You may return any answer array that satisfies this condition.

Example 1:

Input: [3,1,2,4]
Output: [2,4,3,1]
The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted.

Note:

• 1 <= A.length <= 5000
• 0 <= A[i] <= 5000

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Solution

• mine
  • Java
    • Runtime: 1 ms, faster than 99.69%, Memory Usage: 40.5 MB, less than 54.94% of Java online submissions

      //O(N)time
      //O(1)space
      public int[] sortArrayByParity(int[] A) {
          int i = 0;
          for(int j = 0; j < A.length; j++){
              if(A[j] % 2 == 0){
                  swap(A, i, j);
                  i++;
              }
          }
          return A;
      }
      
      void swap(int[] arr, int i, int j){
          if(i == j) return;
          int t = arr[i];
          arr[i] = arr[j];
          arr[j] = t;
      }
      

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