leetcode-169 多数元素 Python

方法一：

class Solution:
def majorityElement(self, nums: List[int]) -> int:
dic = {}
for i in nums:
dic[i] = dic.get(i, 0) + 1
if dic[i] >= len(nums)/2:
return i

方法二：

class Solution:
def majorityElement(self, nums: List[int]) -> int:
if not nums:
return None
dic = {}
for i in nums:
if i not in dic:
dic[i] = 1
else:
dic[i] += 1
max = 0
for key.val in dic.items():
if val > max:
max = val
pos = key
if max > int(len(nums)/2):
return pos

方法三：

class Solution:
def majorityElement(self, nums: List[int]) -> int:
if not nums:
return None
dic = {}
for i in nums:
if i not in dic:
dic[i] = 1
else:
dic[i] += 1
max = 0
for key, val in dic.items():
if val > max:
max = val
pos = key
if max > int(len(nums)/2):
return pos

方法四：投票算法

class Solution:
def majorityElement(self, nums: List[int]) -> int:
m = cm = 0
for num in nums:
if m == num:
cm += 1
elif cm == 0:
m = num
cm = 1
else:
cm -= 1
return m

方法五：排序

class Solution:
def majorityElement(self, nums: List[int]) -> int:
nums.sort()
return nums[len(nums)//2]

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