【LeetCode】27. Remove Element

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本文介绍了一种在原地修改数组的方法，用于移除所有指定值的元素，并返回新的数组长度。通过双指针技巧，该算法仅使用 O(1) 的额外空间实现了这一目标。

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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.

Code:

public int removeElement(int[] nums, int val) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        int j = 0;
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] != val) {
                nums[j++] = nums[i];
            }
        }
        return j;
    }