Leetcode 27——Remove Element

　　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.

分析：in-place就地remove元素，不允许分配另一个数组。可以这么想，允许用另一个数组的话，直接遍历这个数组，满足条件就添加到另一个数组中。但是不让用多一个数组的话，就用自身，因为满足条件的数量肯定是小于等于数组的长度，所以用一个index来计数即可，满足条件的放到index位置上，index++。

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