Fix: make Happy Number code CI-compliant (remove nonstandard headers)

Author: Mojirade18

CPP/Basics/happy_number.cpp

@@ -1,44 +1,45 @@
 // Problem: Happy Number
 // Language: C++
-// Problem: Happy Number (IEEEXtreme / LeetCode 202 style)
 // Description:
-//   A number is "happy" if repeatedly replacing the number by the sum of the
-//   squares of its digits eventually leads to 1. If the process enters a
-//   cycle that does not include 1, the number is not happy.
-// Input/Output for this implementation:
-//   - This program reads a single positive integer n from stdin,
-//     computes whether n is a happy number, and prints "YES" if happy,
-//     otherwise prints "NO".
-// Complexity:
-//   - Each transformation is O(d) where d = number of digits (<= log10 n).
-//   - For base-10 the sequence enters a cycle within limited bounds; overall
-//     expected time is small; space O(1) (Floyd cycle-detection) or O(k) if
-//     using a set where k is number of visited states.
+//   A number is "happy" if repeatedly replacing the number by the sum
+//   of the squares of its digits eventually leads to 1. If it enters
+//   a cycle that does not include 1, the number is not happy.
+// Input: A single positive integer n
+// Output: "YES" if n is a happy number, otherwise "NO"
+
+#include <iostream>
 
-#include <bits/stdc++.h>
 using namespace std;
 
-// compute sum of squares of digits of x
+// Function to compute the sum of squares of digits
 long long sum_of_squares(long long x) {
     long long s = 0;
     while (x > 0) {
-        int d = x % 10;
-        s += 1LL * d * d;
+        int d = static_cast<int>(x % 10);
+        s += static_cast<long long>(d) * d;
         x /= 10;
     }
     return s;
 }
 
-// Approach 1: Floyd's cycle detection (tortoise & hare).
-// If the sequence reaches 1 -> happy. If cycle forms and doesn't include 1 -> not happy.
+// Floyd's cycle detection algorithm
 bool isHappy(long long n) {
-    auto next = [](long long x){ return sum_of_squares(x); };
+    auto next = [](long long x) {
+        long long s = 0;
+        while (x > 0) {
+            int d = static_cast<int>(x % 10);
+            s += static_cast<long long>(d) * d;
+            x /= 10;
+        }
+        return s;
+    };
 
     long long tortoise = n;
     long long hare = n;
+
     while (true) {
-        tortoise = next(tortoise);         // move by 1
-        hare = next(next(hare));          // move by 2
+        tortoise = next(tortoise);
+        hare = next(next(hare));
         if (tortoise == 1 || hare == 1) return true;
         if (tortoise == hare) return false; // cycle detected
     }
@@ -50,6 +51,7 @@ int main() {
 
     long long n;
     if (!(cin >> n)) return 0;
+
     if (n <= 0) {
         cout << "NO\n";
         return 0;
@@ -60,14 +62,8 @@ int main() {
 }
 
 /*
-Sample:
-Input:
+Sample Input:
 19
-Output:
+Sample Output:
 YES
-
-Explanation:
-19 -> 1^2 + 9^2 = 82
-82 -> 8^2 + 2^2 = 68
-68 -> 6^2 + 8^2 = 100
-100 -> 1^2 + 0 + 0 = 1  -> happy
+*/