removeElement.cpp

// 27. Remove Element (https://leetcode.com/problems/remove-element/)
//
// Given an array nums and a value val, 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 1:
//
// Given nums = [3,2,2,3], val = 3,
//
// Your function should return length = 2, with the first two elements of nums being 2.
//
// It doesn't matter what you leave beyond the returned length.
// Example 2:
//
// Given nums = [0,1,2,2,3,0,4,2], val = 2,
//
// Your function should return length = 5, with the first five elements of nums containing 0, 1, 3, 0, and 4.
//
// Note that the order of those five elements can be arbitrary.
//
// It doesn't matter what values are set beyond the returned length.

#include <iostream>
#include <vector>

using namespace std;

int removeElement(vector<int>& nums, int val) {
    if (nums.size() == 0) return 0;
    int len = 0;
    for (int i=0; i<nums.size(); i++) {
        if (nums[i] != val) {
            nums[len++] = nums[i];
        }
    }
    return len;
}

int main() {

    int val = 2;
    int nums[] = {0,1,2,2,3,0,4,2};
    vector<int> v(nums, nums + sizeof(nums)/sizeof(int));

    int length = removeElement(v, val);
    cout << "the new length is " << length << endl;
    for (int i=0; i<length; i++) {
        cout << v[i] << " ";
    }
    cout << endl;

}