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.

输出不是val的元素的个数，并把它们放在数组的前n位

class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        int j=0;   //j代表不是val的元素个数
        for(int i=0;i <nums.capacity();i++){
            if(nums[i]!=val){
                nums[j++]=nums[i];  //把第j个非val的元素放在数组的第j位置
            }
        }
        return j;
        
    }
};