27. Remove Element

Given an array nums and a value val, remove all instances of that value in-place and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

The order of elements can be changed. It doesn't matter what you leave beyond the new length.

Example 1:

Given nums = [3,2,2,3], val = 3,

Your function should return length = 2, with the first two elements of nums being 2.

It doesn't matter what you leave beyond the returned length.

Clarification:

Confused why the returned value is an integer but your answer is an array?

Note that the input array is passed in by reference, which means modification to the input array will be known to the caller as well.

Internally you can think of this:

// nums is passed in by reference. (i.e., without making a copy)
int len = removeElement(nums, val);

// any modification to nums in your function would be known by the caller.
// using the length returned by your function, it prints the first len elements.
for (int i = 0; i < len; i++) {
    print(nums[i]);
}

 

My idea:没什么难的点，主要理解一下为什么返回的值是数组而不是整数，但事实上在py3.6.5里面返回的还是整数

class Solution:
    def removeElement(self, nums: List[int], val: int) -> int:
        while(nums.count(val)!=0):
            nums.remove(val)
        return len(nums)

执行用时 : 100 ms, 在Remove Element的Python3提交中击败了6.12% 的用户

内存消耗 : 12.9 MB, 在Remove Element的Python3提交中击败了98.79% 的用户