# Leetcode: Sort Array By Parity II

Sort Array By Parity II

Similar Problems:

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.
```

Note:

1. 2 <= A.length <= 20000
2. A.length % 2 == 0
3. 0 <= A[i] <= 1000

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

• Solution: array
```// Blog link: https://code.dennyzhang.com/sort-array-by-parity-ii
// Basic Ideas: two pointer
// Move even to the first half, the odd to the second half
// Then swap items
// Complexity: Time O(n), Space O(1)
func sortArrayByParityII(A []int) []int {
l, r := 0, len(A)-1
for l<r {
if A[l] % 2 == 0 {
l++
continue
}
if A[r] % 2 == 1 {
r--
continue
}
A[l], A[r]= A[r], A[l]
l, r = l+1, r-1
}

for i:=1; 2*i<len(A); i+=2 {
j := len(A)-1-i
A[i], A[j] = A[j], A[i]
}
return A
}
```

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