27. Remove Element.cpp

// Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The order of the elements may be changed. Then return the number of elements in nums which are not equal to val.

// Consider the number of elements in nums which are not equal to val be k, to get accepted, you need to do the following things:

// Change the array nums such that the first k elements of nums contain the elements which are not equal to val. The remaining elements of nums are not important as well as the size of nums.
// Return k.
// Custom Judge:

// The judge will test your solution with the following code:

// int[] nums = [...]; // Input array
// int val = ...; // Value to remove
// int[] expectedNums = [...]; // The expected answer with correct length.
//                             // It is sorted with no values equaling val.

// int k = removeElement(nums, val); // Calls your implementation

// assert k == expectedNums.length;
// sort(nums, 0, k); // Sort the first k elements of nums
// for (int i = 0; i < actualLength; i++) {
//     assert nums[i] == expectedNums[i];
// }
// If all assertions pass, then your solution will be accepted.

 

// Example 1:

// Input: nums = [3,2,2,3], val = 3
// Output: 2, nums = [2,2,_,_]
// Explanation: Your function should return k = 2, with the first two elements of nums being 2.
// It does not matter what you leave beyond the returned k (hence they are underscores).
// Example 2:

// Input: nums = [0,1,2,2,3,0,4,2], val = 2
// Output: 5, nums = [0,1,4,0,3,_,_,_]
// Explanation: Your function should return k = 5, with the first five elements of nums containing 0, 0, 1, 3, and 4.
// Note that the five elements can be returned in any order.
// It does not matter what you leave beyond the returned k (hence they are underscores).
 

// Constraints:

// 0 <= nums.length <= 100
// 0 <= nums[i] <= 50
// 0 <= val <= 100



class Solution {
public:
    int removeElement(vector<int>& nums, int val) {
        int n = nums.size();
        int count = 0;
        vector<int> ans;
        
        for(int i=0; i<n; i++){
            if(nums[i]!=val){
                ans.push_back(nums[i]);
                count++;
            }
        }
        nums.clear();
        for(int i=0; i<ans.size(); i++){
            nums.push_back(ans[i]);
        }
        return count;
    }
};