[Swift]LeetCode1207. 独一无二的出现次数 | Unique Number of Occurrences

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Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique.

Example 1:

Input: arr = [1,2,2,1,1,3]
Output: true
Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.

Example 2:

Input: arr = [1,2]
Output: false

Example 3:

Input: arr = [-3,0,1,-3,1,1,1,-3,10,0]
Output: true

Constraints:

• 1 <= arr.length <= 1000
• -1000 <= arr[i] <= 1000

---

给你一个整数数组 arr，请你帮忙统计数组中每个数的出现次数。

如果每个数的出现次数都是独一无二的，就返回 true；否则返回 false。

示例 1：

输入：arr = [1,2,2,1,1,3]
输出：true
解释：在该数组中，1 出现了 3 次，2 出现了 2 次，3 只出现了 1 次。没有两个数的出现次数相同。

示例 2：

输入：arr = [1,2]
输出：false

示例 3：

输入：arr = [-3,0,1,-3,1,1,1,-3,10,0]
输出：true

提示：

• 1 <= arr.length <= 1000
• -1000 <= arr[i] <= 1000

---

Runtime: 12 ms

Memory Usage: 20.7 MB

class Solution {
    func uniqueOccurrences(_ arr: [Int]) -> Bool {
        var freq:[Int:Int] = [Int:Int]()
        for x in arr
        {
            freq[x,default:0] += 1
        }
        var occur:Set<Int> = Set<Int>()
        for (key,val) in freq
        {         
            if occur.contains(val)
            {
                return false
            }
            occur.insert(val)
        }
        return true
    }
} 

---

 12ms

class Solution {
    func uniqueOccurrences(_ arr: [Int]) -> Bool {
        var uniqueDic: [Int: Int] = [:]
      var occurArr = [Int]()
      for num in arr {
        if let occurNum = uniqueDic[num] {
          uniqueDic[num]! = occurNum + 1
        } else {
          uniqueDic[num] = 1
        }
      }
      for (_, value) in uniqueDic {
        if occurArr.contains(value) {
          return false
        }
        occurArr.append(value)
      }
      return true
    
    }
}

---

20ms

class Solution {
    func uniqueOccurrences(_ arr: [Int]) -> Bool {
        var subArray = arr
        var count = arr.count
        var chkCount = count
        var boolArray = Array(repeating: false, count: count)

        for i in arr {
            subArray.removeAll() { $0 == i }
            count = subArray.count

            if chkCount > count {
                if boolArray[chkCount - count] == true {
                    return false
                }
                boolArray[chkCount - count] = true
                chkCount = count
            }
        }
        return true
    }
}