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0169. Majority Element
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0169. Majority Element
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"""Given an array nums of size n, return the majority element.
The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array.
Example 1:
Input: nums = [3,2,3]
Output: 3
Example 2:
Input: nums = [2,2,1,1,1,2,2]
Output: 2
"""
# Boyer–Moore majority vote algorithm
# the majority element always exists in the array.
# 将第一个数假设为major,count major,遇到同样的数,count自增1,否则自减1,
# 如果计数器减到了0,则更换下一个数字为候选者。
class Solution:
def majorityElement(self, nums: List[int]) -> int:
count = 0
for num in nums:
if count == 0:
major = num
count += 1
elif num == major:
count += 1
else:
count -= 1
return major
# Cheating Solution:
class Solution:
def majorityElement(self, nums):
counts = collections.Counter(nums)
return max(counts.keys(), key=counts.get)