Remove Element

Desicription

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:

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Given nums = [3,2,2,3], val = 3,
Your function should return length = 2, with the first two elements of nums being 2.

Solution

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class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        int cnt = 0;
        for(int i = 0 ; i < nums.size() ; ++i) {
            if(nums[i] == val)
                cnt++;
            else
                nums[i-cnt] = nums[i];
        }
        return nums.size()-cnt;
    }
};