remove-element.cpp

// Time:  O(n)
// Space: O(1)

class Solution {
public:
    /**
     *@param A: A list of integers
     *@param elem: An integer
     *@return: The new length after remove
     */
    int removeElement(vector<int> &A, int elem) {
        int left = 0;
        int right = A.size();
        while (left < right) {
            if (A[left] != elem) {
                ++left;
            } else {
                swap(A[left], A[--right]);
            }
        }
        return left;
    }
};