[Swift]LeetCode219. 存在重複元素 II | Contains Duplicate II

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Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.

Example 1:

Input: nums = [1,2,3,1], k = 3 Output: true 

Example 2:

Input: nums = [1,0,1,1], k = 1 Output: true 

Example 3:

Input: nums = [1,2,3,1,2,3], k = 2 Output: false

---

給定一個整數數組和一個整數 k，判斷數組中是否存在兩個不一樣的索引 i 和 j，使得 nums [i] = nums [j]，而且 i 和 j 的差的絕對值最大爲 k。

示例 1:

輸入: nums = [1,2,3,1], k= 3
輸出: true

示例 2:

輸入: nums = [1,0,1,1], k=1
輸出: true

示例 3:

輸入: nums = [1,2,3,1,2,3], k=2
輸出: false

---

 1 class Solution {
 2     func containsNearbyDuplicate(_ nums: [Int], _ k: Int) -> Bool {
 3         //判斷
 4         if nums == nil || nums.count < 2 || k < 1
 5         {
 6             return false
 7         }
 8         var map:[Int:Int] = [Int:Int]()
 9         for i in 0..<(nums.count)
10         {
11             if map.keys.contains(nums[i])
12             {
13                 var sub:Int = i - map[nums[i]]!
14                 if sub <= k
15                 {
16                     return true
17                 }
18                 else
19                 {
20                     map[nums[i]] = i
21                 }
22             }
23             else
24             {
25                 map[nums[i]] = i
26             }
27         }
28         return false
29     }
30 }

---

32ms

 1 class Solution {
 2     func containsNearbyDuplicate(_ nums: [Int], _ k: Int) -> Bool {
 3         var set = Set<Int>()
 4         for i in 0..<nums.count {
 5             if i > k { set.remove(nums[i - k - 1]) }
 6             if !set.insert(nums[i]).inserted { return true }
 7         }
 8         return false
 9     }
10 }

---

32ms

 1 class Solution {
 2     func containsNearbyDuplicate(_ nums: [Int], _ k: Int) -> Bool {
 3         var set = Set<Int>()
 4         
 5         for i in 0..<nums.count {
 6             if i > k {
 7                 set.remove(nums[i - k - 1])
 8             }
 9             if !set.insert(nums[i]).inserted {
10                 return true
11             }
12         }
13         
14         return false
15     }
16 }

---

40ms

 1 class Solution {
 2     func containsNearbyDuplicate(_ nums: [Int], _ k: Int) -> Bool {
 3         var map: [Int:Int] = [:]
 4         
 5         for i in 0..<nums.count {
 6             if let index = map[nums[i]], i - index <= k {
 7                 return true
 8             } else {
 9                 map[nums[i]] = i
10             }
11         }
12         
13         return false
14     }
15 }

---

44ms

 1 class Solution {
 2     func containsNearbyDuplicate(_ nums: [Int], _ k: Int) -> Bool {
 3         var set: Set<Int> = []
 4         for i in 0..<nums.count {
 5             if i > k {
 6                 set.remove(nums[i-k-1])//移掉無效數據
 7             }
 8             if !set.insert(nums[i]).inserted {
 9                 return true
10             }
11         }
12         return false
13     }
14 }