leetcode 1287. Element Appearing More Than 25% In Sorted Array （python）

描述

Given an integer array sorted in non-decreasing order, there is exactly one integer in the array that occurs more than 25% of the time, return that integer.

Example 1:

Input: arr = [1,2,2,6,6,6,6,7,10]
Output: 6	

Example 2:

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

Note:

1 <= arr.length <= 10^4
0 <= arr[i] <= 10^5

解析

根据题意，找出出现次数多于 arr 长度的 25% 的元素。现对 arr 的元素进行计数得到字典 c ，然后遍历 c 找出出现次数满足题意的元素直接返回即可。

解答

class Solution(object):
    def findSpecialInteger(self, arr):
        """
        :type arr: List[int]
        :rtype: int
        """
        N = len(arr)
        t = N * 0.25
        c = collections.Counter(arr)
        for k,v in c.items():
            if v > t:
                return k
        	      
		

运行结果

Runtime: 88 ms, faster than 21.03% of Python online submissions for Element Appearing More Than 25% In Sorted Array.
Memory Usage: 15.6 MB, less than 7.54% of Python online submissions for Element Appearing More Than 25% In Sorted Array.

解析

因为肯定有答案，所以直接找出现次数最多的那个元素即可。

解答

class Solution(object):
    def findSpecialInteger(self, arr):
        """
        :type arr: List[int]
        :rtype: int
        """
        return collections.Counter(arr).most_common(1)[0][0]

运行结果

Runtime: 76 ms, faster than 48.02% of Python online submissions for Element Appearing More Than 25% In Sorted Array.
Memory Usage: 15.5 MB, less than 11.11% of Python online submissions for Element Appearing More Than 25% In Sorted Array.

原题链接：leetcode.com/problems/el…

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