2024-09-09 Leetcode刷题

First Question

快慢指针

class Solution:
    def removeDuplicates(self, nums: List[int]) -> int:
        slow,fast = 0,1
        while fast < len(nums):
            if nums[fast] == nums[slow]:
                fast+=1;
            else:
                nums[slow+1] = nums[fast]
                fast += 1
                slow += 1
        return slow+1

Second Question

利用指针进行计数，后通过所计的数可以很方便的找到要替换的准确的位置

class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        offset = 0
        for i in range(len(nums)):
            if nums[i] == 0:
                offset += 1
            elif nums[i] != 0 and offset > 0:
                nums[i-offset] = nums[i]
                nums[i] = 0

Third Question

要记录的是连续1，所以要在计数该断的时候断（即遇到不是1的时候）

class Solution:
    def findMaxConsecutiveOnes(self, nums: List[int]) -> int:
        max,count = 0,0
        for i in range(len(nums)):
            if nums[i] == 1:
                count += 1
            else:
                count = 0
            if count > max:
                max = count
        return max

Fourth Question

题目只要求前K歌元素包含不等于val的元素，所以只需要把不是val的元素全部放在数组前面，并记录元素个数即可

class Solution:
    def removeElement(self, nums: List[int], val: int) -> int:
        i = 0;
        for x in nums:
            if x != val:
                nums[i] = x
                i+=1
        return i