LeetCode-Easy刷题 Remove Element

Posted 2022-05-31 当以乐

Given an array and a value, 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:

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

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

给定一个数组和一个值，删除该值的所有实例并返回新的长度。 不要为另一个数组分配额外的空间，您必须通过修改带有O(1)额外内存的输入数组来实现这一点。 元素的顺序可以被改变。你在新的长度之外留下什么并不重要。

这题和上题类似通过控制数组的双指针来完成:

    public static int removeElement(int[] nums, int val) 

        if(nums ==null || nums.length<1)
            return 0;
        
        int index = 0;
        for (int i = 0; i < nums.length; i++) 
            if(nums[i]!=val)
                nums[index] = nums[i];
                index++;
            
        
        return index;