#include "soln.hpp" int Solution::missingNumber(vector &nums) { int n = nums.size(); int calc_sum = (n * (n + 1)) / 2; int act_sum = 0; for (int num : nums) { act_sum += num; } return calc_sum - act_sum; } bool Solution::test(vector &nums, int answer) { return missingNumber(nums) == answer; }