LeetCode 1394. Find the lucky number in the array

LeetCode 1394. Find the lucky number in the array

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• Question :
  In an integer array, if the frequency of occurrence of an integer is equal to its numerical value, we call this integer a "lucky number".
  Give you an array of integers arr, please find out and return a lucky number from it.
  • If there are multiple array lucky number, simply return the biggest one.
  • If there is no lucky number in the array, -1 is returned .
• Example :

示例 1 :
输入：arr = [2,2,3,4]
输出：2
解释：数组中唯一的幸运数是 2 ，因为数值 2 的出现频次也是 2 。

示例 2 :
输入：arr = [1,2,2,3,3,3]
输出：3
解释：1、2 以及 3 都是幸运数，只需要返回其中最大的 3 。

示例 3 :
输入：arr = [2,2,2,3,3]
输出：-1
解释：数组中不存在幸运数。

示例 4 :
输入：arr = [5]
输出：-1

示例 5 :
输入：arr = [7,7,7,7,7,7,7]
输出：7

• Tips :
  • 1 <= arr.length <= 500
  • 1 <= arr[i] <= 500
• Code 1:

class Solution:
    def findLucky(self, arr: List[int]) -> int:
        result = []
        for i in range(len(arr)):
            if arr.count(arr[i]) == arr[i]:
                result.append(arr[i])
        if result == []:
            return -1
        return max(result)
# 执行用时 :160 ms, 在所有 Python3 提交中击败了6.10%的用户
# 内存消耗 :13.7 MB, 在所有 Python3 提交中击败了100.00%的用户

• Algorithm description:
  Count the number of occurrences of the current element arr[i]in the list . If the value of the element is equal to the number of occurrences, store the element in the list and return the largest element in the list .arrarr.count(arr[i])resultresult