leetcode题解-26. Remove Duplicates from Sorted Array && 27. Remove Element

Remove Duplicates from Sorted Array，题目：

Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this in place with constant memory.

For example,
Given input array nums = [1,1,2],

Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively. It doesn't matter what you leave beyond the new length.

本题是要从一个排序数组中将重复元素去掉，仅保存一个值，并返回最后的数组长度。注意这里不能占用额外的空间，只能在原数组内进行替换。因为数组已经排序，所以我们判断两个相邻元素是否相等即可，并使用len来记录当前数组长度，并将不同元素替换到len位置处，加一。代码入下：

    public static int removeDuplicates(int[] nums) {
        int len = nums.length > 0 ? 1 : 0;
        for(int n:nums){
            if(n > nums[len-1])
                nums[len++] = n;
        }
        return len;
    }

Remove Element 题目：

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 in place with constant memory.

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

Example:
Given input array nums = [3,2,2,3], val = 3

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

本题与上一题相似，一个是移除重复元素，一个是移除某个元素。相比之下本体更简单。代码入下：

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