[Swift]LeetCode1089. 複寫零 | Duplicate Zeros

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Given a fixed length array arr of integers, duplicate each occurrence of zero, shifting the remaining elements to the right.

Note that elements beyond the length of the original array are not written.

Do the above modifications to the input array in place, do not return anything from your function. 

Example 1:

Input: [1,0,2,3,0,4,5,0] Output: null Explanation: After calling your function, the input array is modified to: [1,0,0,2,3,0,0,4] 

Example 2:

Input: [1,2,3] Output: null Explanation: After calling your function, the input array is modified to: [1,2,3] 

Note:

1. 1 <= arr.length <= 10000
2. 0 <= arr[i] <= 9

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給你一個長度固定的整數數組 arr，請你將該數組中出現的每一個零都複寫一遍，並將其他的元素向右平移。

注意：請不要在超過該數組長度的位置寫入元素。

要求：請對輸入的數組 就地 進行上述修改，不要從函數返回任何東西。 

示例 1：

輸入：[1,0,2,3,0,4,5,0]
輸出：null
解釋：調用函數後，輸入的數組將被修改成：[1,0,0,2,3,0,0,4]

示例 2：

輸入：[1,2,3]
輸出：null
解釋：調用函數後，輸入的數組將被修改成：[1,2,3] 

提示：

1. 1 <= arr.length <= 10000
2. 0 <= arr[i] <= 9

---

Runtime: 40 ms

Memory Usage: 21.1 MB

 1 class Solution {  2  func duplicateZeros(_ arr: inout [Int]) {  3         var n:Int = arr.count  4         var a:[Int] = arr  5         var p:Int = 0
 6         for i in 0..<n  7  {  8             if a[i] == 0
 9  { 10                 if p < n 11  { 12                     arr[p] = 0
13                     p += 1
14  } 15                 if p < n 16  { 17                     arr[p] = 0
18                     p += 1
19  } 20  } 21             else
22  { 23                 if p < n 24  { 25                     arr[p] = a[i] 26                     p += 1
27  } 28  } 29  } 30         
31  } 32 }

---

44ms

 

 1 class Solution {  2  func duplicateZeros(_ arr: inout [Int]) {  3         let c = arr.count  4         if c <= 1 { return }  5 
 6         var i = 0
 7         while i < c {  8             if arr[i] == 0 {  9                 arr.insert(0, at: i) 10                 i += 2
11             } else { 12                 i += 1
13  } 14  } 15         while arr.count > c { 16             _ = arr.popLast() 17  } 18  } 19 }

---

48ms

 1 class Solution {  2  func duplicateZeros(_ arr: inout [Int]) {  3         var count = 0
 4         for (index, value) in arr.enumerated() {  5             if value == 0 {  6                 count += 1
 7  }  8  }  9         var index = arr.count - 1
10         while index >= 0 { 11             let value = arr[index] 12             if index + count < arr.count { 13                 arr[index + count] = value 14  } 15             if value == 0 { 16                 count -= 1
17                 if index + count < arr.count { 18                     arr[index + count] = 0
19  } 20  } 21             index -= 1
22  } 23  } 24 }