[Swift]LeetCode283. 移动零 | Move Zeroes

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Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.

Example:

Input: [0,1,0,3,12]
Output: [1,3,12,0,0]

Note:

1. You must do this in-place without making a copy of the array.
2. Minimize the total number of operations.

---

给定一个数组 nums，编写一个函数将所有 0 移动到数组的末尾，同时保持非零元素的相对顺序。

示例:

输入: [0,1,0,3,12]
输出: [1,3,12,0,0]

说明:

1. 必须在原数组上操作，不能拷贝额外的数组。
2. 尽量减少操作次数。

---

16ms

class Solution {
    func moveZeroes(_ nums: inout [Int]) {
        //0要后移，反意是非0元素前移。
        if nums == nil || nums.count == 0
        {
            return
        }
        //记录非0元素开始位置
        var j:Int = 0
        for i in 0..<nums.count
        {
            if nums[i] != 0
            {             
                nums[j] = nums[i]
                j += 1
            }
        }
        while(j < nums.count)
        {
            nums[j] = 0
            j += 1
        }
    }
}

---

16ms

class Solution {
    func moveZeroes(_ nums: inout [Int]) {
        var firstPointer = 0 
        var secondPointer = 0
         
        while secondPointer < nums.count {
            if nums[firstPointer] == 0 {
                if nums[secondPointer] != 0 {
                    swap(&nums, firstPointer, secondPointer)
                } else {
                    secondPointer += 1
                }
            } else {
                secondPointer += 1
                firstPointer += 1
            }
        }
    }
    
    func swap(_ nums: inout [Int], _ firstIndex: Int, _ secondIndex: Int) {
        var temp = nums[firstIndex]
        nums[firstIndex] = nums[secondIndex]
        nums[secondIndex] = temp
    }
}

---

16ms

class Solution {
    func moveZeroes(_ nums: inout [Int]) {
        var index1 = 0
        var index2 = nums.count
        while index1 <= index2 - 1 {
            if nums[index1] == 0 {
                for _ in 0..<(index2-index1) {
                    index2 -= 1
                    if nums[index2] != 0 {
                        nums.remove(at: index1)
                        nums.append(0)
                        break;
                    }
                }
            }else {
                index1 += 1
            }
        }
    }
}

---

20ms

class Solution {
    func moveZeroes(_ nums: inout [Int]) {
        var removedCount = 0
        for (idx, val) in nums.enumerated() {
            if val == 0 {
                nums.remove(at: idx-removedCount)
                removedCount += 1
                nums.append(0)
            }
        }
    }
}