day 35: 202-happy-number

202-happy-number/driver.cpp

@@ -0,0 +1,10 @@
+#include "soln.hpp"
+
+int main()
+{
+	int n = 42;
+	bool answer = false;
+	Solution soln;
+	cout << "Checked happy number correctly? " << soln.test(n, answer) << endl;
+	return 0;
+}

202-happy-number/soln.cpp

@@ -0,0 +1,33 @@
+#include "soln.hpp"
+
+bool Solution::isHappy(int n)
+{
+	// naive
+	unordered_map<int, bool> occurrences{{n, true}};
+	int tmp, tmp_sum;
+	while (n != 1)
+	{
+		tmp = n;
+		tmp_sum = 0;
+		while (tmp > 0)
+		{
+			tmp_sum += (tmp % 10) * (tmp % 10);
+			tmp /= 10;
+		}
+		// cycle
+		if (occurrences.find(tmp_sum) != occurrences.end())
+		{
+			return false;
+		}
+		occurrences[tmp_sum] = true;
+		n = tmp_sum;
+	}
+	return n == 1;
+
+	// floyd cycle finding is better
+}
+
+bool Solution::test(int n, bool answer)
+{
+	return isHappy(n) == answer;
+}

202-happy-number/soln.hpp

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