day 26: 268-missing-number, 15-3-sum

268-missing-number/driver.cpp

@@ -0,0 +1,10 @@
+#include "soln.hpp"
+
+int main()
+{
+	vector<int> nums{9, 6, 4, 2, 3, 5, 7, 0, 1};
+	int answer = 8;
+	Solution soln;
+	cout << "Found missing number correctly? " << soln.test(nums, answer) << endl;
+	return 0;
+}

268-missing-number/soln.cpp

@@ -0,0 +1,18 @@
+#include "soln.hpp"
+
+int Solution::missingNumber(vector<int> &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<int> &nums, int answer)
+{
+	return missingNumber(nums) == answer;
+}

268-missing-number/soln.hpp

@@ -0,0 +1,8 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution
+{
+public:
+	int missingNumber(vector<int> &nums);
+	bool test(vector<int> &nums, int answer);
+};