leetcode刷题记录161-170 python版

前言

继续leetcode刷题生涯
这里记录的都是笔者觉得有点意思的做法
参考了好几位大佬的题解，尤其是powcai大佬和labuladong大佬，感谢各位大佬

162. 寻找峰值

# 二分 局部最大
class Solution(object):
    def findPeakElement(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        l, r = 0, len(nums) - 1
        while l < r:
            mid = l + (r - l) // 2
            if nums[mid] < nums[mid + 1]:
                l = mid + 1
            else:
                r = mid
        return l

164. 最大间距

# 桶排序
class Solution(object):
    def maximumGap(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        n = len(nums)
        if n <= 1: return 0
        max_num = max(nums)
        min_num = min(nums)
        import math
        gap = math.ceil((max_num - min_num) / (n - 1))
        bucket = [[float("inf"), float("-inf")] for _ in range(n-1)]
        for i in nums:
            if i == max_num or i == min_num:
                continue
            loc = (i - min_num) // gap
            bucket[loc][0] = min(i, bucket[loc][0])
            bucket[loc][1] = max(i, bucket[loc][1])
        premin = min_num
        res = float("-inf")
        for x, y in bucket:
            if x == float("inf"):
                continue
            res = max(res, x - premin)
            premin = y
        res = max(res, max_num - premin)
        return res

165. 比较版本号

class Solution(object):
    def compareVersion(self, version1, version2):
        """
        :type version1: str
        :type version2: str
        :rtype: int
        """
        import itertools
        l1, l2 = version1.split("."), version2.split(".")
        for x, y in itertools.zip_longest(l1, l2, fillvalue=0):
            if int(x) != int(y):
                if int(x) > int(y):
                    return 1
                else:
                    return -1
        return 0

166. 分数到小数

class Solution:
    def fractionToDecimal(self, numerator: int, denominator: int) -> str:
        if numerator == 0: return "0"
        res = []
        if (numerator > 0) ^ (denominator > 0):
            res.append("-")
        numerator, denominator = abs(numerator), abs(denominator)
        a, b = divmod(numerator, denominator)
        res.append(str(a))
        if b == 0:
            return "".join(res)
        res.append(".")
        loc = {b:len(res)}
        while b:
            b *= 10
            a, b = divmod(b, denominator)
            res.append(str(a))
            if b in loc:
                res.insert(loc[b], "(")
                res.append(")")
                break
            loc[b] = len(res)
        return "".join(res)

167. 两数之和 II - 输入有序数组

class Solution:
    def twoSum(self, numbers: List[int], target: int) -> List[int]:
        l, r = 0 ,len(numbers) - 1
        while l < r:
            res = numbers[l] + numbers[r]
            if res == target:
                return [l+1, r+1]
            elif res > target:
                r -= 1
            else:
                l += 1

168. Excel表列名称

# 10进制转换26进制
class Solution:
    def convertToTitle(self, n: int) -> str:
        res = ""
        while n:
            n -= 1
            n, y = divmod(n, 26)
            res = chr(y + 65) + res
        return res
# 递归
class Solution:
    def convertToTitle(self, n: int) -> str:
        return "" if n == 0 else self.convertToTitle((n - 1) // 26) + chr((n - 1) % 26 + 65)

169. 多数元素

# 排序中位数
class Solution:
    def majorityElement(self, nums: List[int]) -> int:
        return sorted(nums)[len(nums)//2]
# 计数
class Solution:
    def majorityElement(self, nums: List[int]) -> int:
        return sorted(collections.Counter(nums).items(), key = lambda x:x[1])[-1][0]