LeetCode 27. Remove Element

最新推荐文章于 2025-08-31 17:43:57 发布

原创最新推荐文章于 2025-08-31 17:43:57 发布 · 161 阅读

0 ·

CC 4.0 BY-SA版权

AC路漫漫专栏收录该内容

180 篇文章

订阅专栏

博客围绕给定整数数组和特定值展开，要求在不额外分配数组空间的情况下，原地移除数组中所有该特定值的实例，并返回新数组的长度。元素顺序可改变，超出新长度的元素无需关注。

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.

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.

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]);
}

给定整数数组和一个特定值，原地移除所有给定的特定值实例，并且返回新数组长度。

//Java
class Solution {
    public int removeElement(int[] nums, int val) {
        int idx = nums.length - 1;
        for (int i = 0; i <= idx; i++) {
            if (nums[i] == val) {
                if (nums[i] == nums[idx]) {
                    i--;
                } else {
                    nums[i] = nums[idx];
                }
                idx--;
            }
        }
        
        return idx + 1;
    }
}