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  • 【leetcode】1394. Find Lucky Integer in an Array

    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: -1
    

    Example 5:

    Input: arr = [7,7,7,7,7,7,7]
    Output: 7

    Constraints:

    • 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
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  • 原文地址:https://www.cnblogs.com/seyjs/p/12631461.html
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