ERROR: AddressSanitizer: negative-size-param: (size=-4)

Question

Trying to write some code, and erase() is giving me a runtime error. What's wrong with the way I used erase?

class Solution {
    public:
        vector<int> findDisappearedNumbers(vector<int>& nums) {
            int size = nums.size();
            vector<int> list; 
            for(int i = 1; i <= size; i++)
                list.push_back(i);
            for(int i = 0; i < size; i++) {
                int num = nums[i];
                list[num - 1] = 0;
            }
            for(int i = 0; i < size; i++) {
                if(list[i] == 0) {
                    list.erase(list.begin() + i);
                }
            }
            return list;
        }
    };

Here's the problem I am trying to solve

Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.

Find all the elements of [1, n] inclusive that do not appear in this array.

Could you do it without extra space and in O(n) runtime? You may assume the returned list does not count as extra space.

Example:

Input: [4,3,2,7,8,2,3,1]

Output: [5,6]

Answer 1

Since all the non solutions were marked 0, you can remove all 0's in the vector using list.erase( remove (list.begin(), list.end(), 0), list.end() );