# LeetCode Solution, Easy, 905. Sort Array By Parity

# [905. Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity/)

## 題目敘述

Given an integer array `nums`, move all the even integers at the beginning of the array followed by all the odd integers.

Return _**any array** that satisfies this condition_.

**Example 1:**

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

**Example 2:**

    Input: nums = [0]
    Output: [0]

**Constraints:**

- `1 <= nums.length <= 5000`
- `0 <= nums[i] <= 5000`

### 題目翻譯

這題是有一個整數陣列 `nums`，要將其中偶數元素往前挪移，奇數往後排序。其中偶數元素間或奇數元素間的排序不要求。

## 解法解析

這題跟上一篇 [Move Zeroes](https://blog.taiwolskit.com/leetcode-solution-easy-283-move-zeroes) 有 78 成相似，所以可以互相參考一下。但因為不考慮元素間的排序，所以處理方式相對簡單。

### 解法範例

#### Go

##### Sort

```go
func sortArrayByParity(nums []int) []int {
	sort.Slice(nums, func(i, j int) bool {
		return nums[i]%2 < nums[j]%2
	})
	return nums
}
```

##### Two Pointers

```go
func sortArrayByParity(nums []int) []int {
	even := []int{}
	odd := []int{}

	for _, v := range nums {
		if v%2 == 0 {
			even = append(even, v)
		} else {
			odd = append(odd, v)
		}
	}

	return append(even, odd...)
}
```

##### In Place

```go
func sortArrayByParity(nums []int) []int {
	for i, j := 0, len(nums)-1; i < j; {
		if nums[i]%2 > nums[j]%2 {
			nums[i], nums[j] = nums[j], nums[i]
		}
		if nums[i]%2 == 0 {
			i++
		}
		if nums[j]%2 == 1 {
			j--
		}
	}
	return nums
}
```

#### JavaScript

##### Sort

```javascript
/**
 * @param {number[]} nums
 * @return {number[]}
 */
var sortArrayByParity = function (nums) {
    nums.sort((a, b) => (a % 2) - (b % 2));
    return nums;
};
```

##### Two Pointers

```javascript
/**
 * @param {number[]} nums
 * @return {number[]}
 */
var sortArrayByParity = function (nums) {
    const result = new Array();
    nums.forEach((e) => {
        if (e % 2 == 1) {
            result.push(e);
        } else {
            result.unshift(e);
        }
    });

    return result;
};
```

##### In Place

```javascript
/**
 * @param {number[]} nums
 * @return {number[]}
 */
var sortArrayByParity = function (nums) {
    let i = 0,
        j = nums.length - 1;
    while (i < j) {
        if (nums[i] % 2 > nums[j] % 2) {
            [nums[i], nums[j]] = [nums[j], nums[i]];
        }
        if (nums[i] % 2 == 0) {
            i++;
        }
        if (nums[j] % 2 == 1) {
            j--;
        }
    }
    return nums;
};
```

#### Kotlin

##### Sort

```kotlin
class Solution {
    fun sortArrayByParity(nums: IntArray): IntArray {
        return nums.sortedBy { it % 2 }.toIntArray()
    }
}
```

##### Two Pointers

```kotlin
class Solution {
    fun sortArrayByParity(nums: IntArray): IntArray {
        return nums.filter { it % 2 == 0 }.toIntArray().plus(nums.filter { it % 2 == 1 })
    }
}
```

##### In Place

```kotlin
class Solution {
    fun sortArrayByParity(nums: IntArray): IntArray {
        var i = 0
        var j = nums.size - 1
        while (i < j) {
            if (nums[i] % 2 > nums[j] % 2) {
                nums[i] = nums[j].also { nums[j] = nums[i] }
            }
            if (nums[i] % 2 == 0) {
                i++
            }
            if (nums[j] % 2 == 1) {
                j--
            }
        }
        return nums
    }
}
```

#### PHP

##### Sort

```php
class Solution
{

    /**
     * @param Integer[] $nums
     * @return Integer[]
     */
    function sortArrayByParity($nums)
    {
        usort($nums, function ($a, $b) {
            return ($a % 2) - ($b % 2);
        });
        return $nums;
    }
}
```

##### Two Pointers

```php
class Solution
{

    /**
     * @param Integer[] $nums
     * @return Integer[]
     */
    function sortArrayByParity($nums)
    {
        $even = [];
        foreach ($nums as $num) {
            if ($num % 2 === 0) {
                $even[] = $num;
            }
        }
        return array_merge($even, array_diff($nums, $even));
    }
}
```

##### In Place

```php
class Solution
{

    /**
     * @param Integer[] $nums
     * @return Integer[]
     */
    function sortArrayByParity($nums)
    {
        $i = 0;
        $j = count($nums) - 1;
        while ($i < $j) {
            if ($nums[$i] % 2 > $nums[$j] % 2) {
                $tmp = $nums[$i];
                $nums[$i] = $nums[$j];
                $nums[$j] = $tmp;
            }

            if ($nums[$i] % 2 === 0) {
                $i++;
            }
            if ($nums[$j] % 2 === 1) {
                $j--;
            }
        }

        return $nums;
    }
}
```

#### Python

##### Sort

```python
class Solution:
    def sortArrayByParity(self, nums: List[int]) -> List[int]:
        nums.sort(key=lambda x: x % 2)
        return nums
```

##### Two Pointers

```python
class Solution:
    def sortArrayByParity(self, nums: List[int]) -> List[int]:
        return [x for x in nums if x % 2 == 0] + [x for x in nums if x % 2 == 1]
```

##### In Place

```python
class Solution:
    def sortArrayByParity(self, nums: List[int]) -> List[int]:
        i, j = 0, len(nums) - 1
        while i < j:
            if nums[i] % 2 > nums[j] % 2:
                nums[i], nums[j] = nums[j], nums[i]

            if nums[i] % 2 == 0:
                i += 1
            if nums[j] % 2 == 1:
                j -= 1

        return nums
```

#### Rust

```rust
```

#### Swift

##### Sort

```swift
class Solution {
    func sortArrayByParity(_ nums: [Int]) -> [Int] {
        return nums.sorted {
            $0 % 2 < $1 % 2
        }
    }
}
```

##### Two Pointers

```swift
class Solution {
    func sortArrayByParity(_ nums: [Int]) -> [Int] {
        return nums.filter { $0 % 2 == 0 } + nums.filter { $0 % 2 == 1 }
    }
}
```

##### In Place

```swift
class Solution {
    func sortArrayByParity(_ nums: [Int]) -> [Int] {
        var i: Int = 0
        var j: Int = nums.count - 1
        var nums: [Int] = nums
        while i < j {
            if nums[i] % 2 == 0 {
                i += 1
            } else {
                nums.swapAt(i, j)
                j -= 1
            }
        }
        return nums
    }
}
```