Find all numbers disappeared in an array.

Author: recherst

Easy/448.Find All Numbers Disappeared in an Array.playground/Contents.swift

@@ -0,0 +1,37 @@
+/**
+ Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums.
+
+  
+
+ Example 1:
+ Input: nums = [4,3,2,7,8,2,3,1]
+ Output: [5,6]
+ 
+ Example 2:
+ Input: nums = [1,1]
+ Output: [2]
+  
+
+ Constraints:
+ - n == nums.length
+ - 1 <= n <= 105
+ - 1 <= nums[i] <= n
+  
+
+ Follow up: Could you do it without extra space and in O(n) runtime? You may assume the returned list does not count as extra space.
+ */
+class Solution {
+    func findDisappearedNumbers(_ nums: [Int]) -> [Int] {
+        var arr = nums
+        for n in arr {
+            arr[abs(n) - 1] = -abs(arr[abs(n) - 1])
+        }
+        var res = [Int]()
+        for i in 0..<arr.count {
+            if arr[i] > 0 {
+                res.append(i + 1)
+            }
+        }
+        return res
+    }
+}

Easy/448.Find All Numbers Disappeared in an Array.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

Easy/448.Find All Numbers Disappeared in an Array.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -89,6 +89,7 @@
 85. [Add Strings](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/415.Add%20Strings.playground/Contents.swift)
 86. [Number of Segments in a String](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/434.Number%20of%20Segments%20in%20a%20String.playground/Contents.swift)
 87. [Arranging Coins](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/441.Arranging%20Coins.playground/Contents.swift)
+88. [Find All Numbers Disappeared in an Array](https://github.com/recherst/leetcode-algtorithm/blob/main/Easy/448.Find%20All%20Numbers%20Disappeared%20in%20an%20Array.playground/Contents.swift)
 
 #### Medium