Given an integer array
nums and an integer
val, remove all occurrences of
nums in-place. The relative order of the elements may be changed.
Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the first part of the array
nums. More formally, if there are
k elements after removing the duplicates, then the first
k elements of
nums should hold the final result. It does not matter what you leave beyond the first
k after placing the final result in the first
k slots of
Do not allocate extra space for another array. You must do this by modifying the input array in-place with O(1) extra memory.
def removeElement(cls, nums: List[int], val: int) -> int: fast = slow = 0 while fast < len(nums): if nums[fast] != val: nums[slow] = nums[fast] slow += 1 # when fast pointer meet the element we want to delete, we stop assign value # slow pointer stops, fast keep moving fast += 1 return slow