leetcode 27 remove element

题目

Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The order of the elements may be changed. Then return the number of elements in nums which are not equal to val.
Consider the number of elements in nums which are not equal to val be k, to get accepted, you need to do the following things:
Change the array nums such that the first k elements of nums contain the elements which are not equal to val. The remaining elements of nums are not important as well as the size of nums.
Return k.

给了特别特别多的提示，

解法

可以看到只需要验证前几位是不等于val的，同时需要这个前几位的长度。
所以只要把不等于val的所有填到前几位就行：

class Solution(object):
    def removeElement(self, nums, val):
        """
        :type nums: List[int]
        :type val: int
        :rtype: int
        """

        index = 0
        for i in range(len(nums)):
            if nums[i] != val:
                nums[index] = nums[i]
                index += 1
        
        return index
    
        return index