[Swift]LeetCode217. 存在重複元素 | Contains Duplicate

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Given an array of integers, find if the array contains any duplicates.

Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

Example 1:

Input: [1,2,3,1]
Output: true

Example 2:

Input: [1,2,3,4]
Output: false

Example 3:

Input: [1,1,1,3,3,4,3,2,4,2]
Output: true

---

給定一個整數數組，判斷是否存在重複元素。

若是任何值在數組中出現至少兩次，函數返回 true。若是數組中每一個元素都不相同，則返回 false。

示例 1:

輸入: [1,2,3,1]
輸出: true

示例 2:

輸入: [1,2,3,4]
輸出: false

示例 3:

輸入: [1,1,1,3,3,4,3,2,4,2]
輸出: true

---

168ms

1 class Solution {
2     func containsDuplicate(_ nums: [Int]) -> Bool {
3         return Set(nums).count != nums.count
4     }
5 }

---

176ms

 1 class Solution {
 2     func containsDuplicate(_ nums: [Int]) -> Bool {
 3         
 4         if nums.count == 0 {
 5             return false
 6         }
 7         
 8         var dict: Set<Int> = Set()
 9         
10         for item in nums {
11             dict.insert(item)
12         }
13         
14         if dict.count < nums.count {
15             return true
16         }
17         
18         
19         return false
20     }
21 }

---

180ms

 1 class Solution {
 2     func containsDuplicate(_ nums: [Int]) -> Bool {
 3         guard nums.count > 1 else {
 4             return false
 5         }
 6         var  set = Set([Int]())
 7         for num in nums {
 8             if set.contains( num) {
 9                 return true
10             } else {
11                 set.insert(num)
12             }
13         }
14         return false
15     }
16 }