Remove Element

 1 class Solution 
 2 {
 3 public:
 4     int removeElement(vector<int>& nums, int val) 
 5     {
 6         int len = nums.size();
 7         int i = 0;
 8         while(i < len)
 9             nums[i] == val? (nums[i] = nums[--len]): ++i;
10         return len;
11     }
12 };

从后往前填充

https://leetcode.com/problems/remove-element/