feat: add reverse_integer

operations_on_datastructures/reverse_integer.cpp

@@ -0,0 +1,85 @@
+/**
+ * @file
+ * @brief Provides a function to reverse the digits of a 32-bit integer safely.
+ *
+ * This implementation reverses the digits of an integer while preventing
+ * overflow by checking limits against INT32_MAX and INT32_MIN.
+ *
+ * @author [Rfontt](https://github.com/Rfontt)
+ */
+
+#include <cassert>
+#include <iostream>
+#include <limits>
+
+/**
+ * @brief Reverses the digits of a 32-bit signed integer.
+ *
+ * This function extracts digits one by one from the input integer and builds
+ * the reversed number. Before each multiplication and addition, it checks
+ * whether the operation would overflow a 32-bit signed integer. If an overflow
+ * would occur, the function returns 0.
+ *
+ * @param number The integer whose digits will be reversed.
+ * @return The reversed integer, or 0 if the reversal would overflow.
+ */
+int reverse(int number) {
+    int32_t reversed = 0;
+
+    while (number != 0) {
+        int digit = number % 10;
+
+        if (reversed > INT32_MAX / 10 || reversed < INT32_MIN / 10) {
+            return 0;
+        }
+
+        reversed = reversed * 10 + digit;
+
+        number = number / 10;
+    }
+
+    return reversed;
+}
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+void test() {
+    // Positive numbers
+    assert(reverse(123) == 321);
+    assert(reverse(1) == 1);
+    assert(reverse(10) == 1);
+
+    // Negative numbers
+    assert(reverse(-123) == -321);
+    assert(reverse(-10) == -1);
+
+    // Edge cases
+    assert(reverse(0) == 0);
+
+    // Reverse of 1534236469 would overflow 32-bit
+    assert(reverse(1534236469) == 0);
+
+    // Reverse of INT32_MAX (2147483647) also overflows
+    assert(reverse(std::numeric_limits<int>::max()) == 0);
+
+    // Reverse of INT32_MIN (−2147483648) also overflows
+    assert(reverse(std::numeric_limits<int>::min()) == 0);
+
+    // Palindromes
+    assert(reverse(1221) == 1221);
+    assert(reverse(-1221) == -1221);
+
+    std::cout << "All tests passed!\n";
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();
+
+    return 0;
+}