905. Sort Array By Parity

Problem 905

https://leetcode.com/problems/sort-array-by-parity/ 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.

Solution

list

class Solution(object):
    def sortArrayByParity(self, A):
        Ans = []
        for a in A:
            if a%2:
                Ans.append(a)
            else:
                Ans.insert(0,a)
        
        return Ans

# solution by two pass        
class Solution_two(object):
    def sortArrayByParity(self, A):
        Ans = [ x for x in A if x % 2 == 0 ] + [ x for x in A if x % 2 == 1 ]
        return Ans

# solution by two list        
class Solution_list(object):
    def sortArrayByParity(self, A):
        even, odd = [], []
        for a in A:
            if a % 2: odd.append(a)
            else: even.append(a)
        return even + odd

in-place

class Solution_in_place(object):
    def sortArrayByParity(self, A):
        l,r = 0, len(A) -1
        while l < r:
            if A[l] % 2 > A[r] % 2:
                A[l], A[r] = A[r], A[l]
                l += 1
                r -= 1
            elif A[l] % 2 == 0:
                l += 1
            elif A[r] % 2 == 1:
                r -= 1
        return A

sort

class Solution_sort(object):
    def sortArrayByParity(self, A):
        A.sort( key= lambda a : a%2 )
        
        return A