Ab82c260f6f094e822d625ad3b9916bf
(难度Easy) Problem 27. Remove Element (去除数组中元素)

链接

https://leetcode.com/problems/remove-element/

难度等级

Easy

题干

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.

题意

给定一个数组和一个值val,要求从数组中去掉val,并且返回操作之后数组中剩下的元素个数。

要求不能申请额外的数组,只能在$O(1)$的复杂度当中替换原数组的值。

样例

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.
Example 2:

Given nums = [0,1,2,2,3,0,4,2], val = 2,

Your function should return length = 5, with the first five elements of nums containing 0, 1, 3, 0, and 4.

Note that the order of those five elements can be arbitrary.

It doesn't matter what values are set beyond the returned length.

注意

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:

top Created with Sketch.