[LeetCode]#922. Sort Array By Parity II

Environment: Python 3.8

Key technique: %

Given an array A of non-negative integers, half of the integers in A are odd, and half of the integers are even.

Sort the array so that whenever A[i] is odd, i is odd; and whenever A[i] is even, i is even.

You may return any answer array that satisfies this condition.

Example 1:

Input: [4,2,5,7]
Output: [4,5,2,7]
Explanation: [4,7,2,5], [2,5,4,7], [2,7,4,5] would also have been accepted.

Analysis:

1. Create a None list and size is same as input A.
2. Create two variable t1=0, t2=1.
3. If A[i] is even, ans[t1] is A[i]. t1=t1+2
4. If A[i] is odd, ans[t2] is A[i]. t2=t2+2
5. Return ans

Solution:

class Solution:
    def sortArrayByParityII(self, A):
        ans=[None]*len(A)
        t1=0
        t2=1
        for i in A:
            if i % 2==0:
                ans[t1]=i
                t1+=2
            else:
                ans[t2]=i
                t2+=2
        return ans

Submissions:

Reference:

https://leetcode.com/problems/sort-array-by-parity-ii/discuss/1003699/Python-3-two-pointers-O(n)