【python刷题】数组链表去重

数组去重

def removeDuplicates(nums):
    n = len(nums)
    if n == 0:
        return 0
    slow,fast = 0,1
    while fast < n:
        if nums[fast] != nums[slow]:
            slow += 1
            nums[slow] = nums[fast]
        fast += 1
    return slow + 1

nums = [0,0,1,1,1,1,2,2,3,3,3,4]
res = removeDuplicates(nums)
print(nums[:res])

链表去重

def deleteDuplicates(head):
    if not head:
        return None
    slow = head
    fast = head.next
    while fast != None:
        if fast.val == slow.val:
            slow.next = fast
            slow = slow.next
        fast = fast.next
    slow.next = None
    return head

leetcode 316 去除重复字母

class Solution:
    def removeDuplicateLetters(self, s: str) -> str:
        from collections import Counter
        stack = []
        instack = {chr(i):-1 for i in range(256)}
        count = Counter(s)
        for c in s:
            count[c] -= 1
            if instack[c] == 1:
                continue
            while len(stack) > 0 and stack[-1] > c:
                if count[stack[-1]] == 0:
                    break
                instack[stack.pop()] = 0
            stack.append(c)
            instack[c] = 1
        return "".join(stack)

leetcode 27 移动元素

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

leetcode 283 移动0

class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        slow, fast = 0,0
        while fast < len(nums):
            if nums[fast] != 0:
                nums[slow],nums[fast] = nums[fast],nums[slow]
                slow += 1
            fast += 1