题目如下:
Given an array of integers
arr
, a lucky integer is an integer which has a frequency in the array equal to its value.Return a lucky integer in the array. If there are multiple lucky integers return the largest of them. If there is no lucky integer return -1.
Example 1:
Input: arr = [2,2,3,4] Output: 2 Explanation: The only lucky number in the array is 2 because frequency[2] == 2.Example 2:
Input: arr = [1,2,2,3,3,3] Output: 3 Explanation: 1, 2 and 3 are all lucky numbers, return the largest of them.Example 3:
Input: arr = [2,2,2,3,3] Output: -1 Explanation: There are no lucky numbers in the array.Example 4:
Input: arr = [5] Output: -1Example 5:
Input: arr = [7,7,7,7,7,7,7] Output: 7Constraints:
1 <= arr.length <= 500
1 <= arr[i] <= 500
解题思路:非常简单的题目。
代码如下:
class Solution(object): def findLucky(self, arr): """ :type arr: List[int] :rtype: int """ val = [0] * 501 for i in arr: val[i] += 1 for inx in range(len(val)-1,0,-1): if inx == val[inx]: return inx return -1