day 2 commit & changed day 1 filenames

D2_power.cpp

@@ -0,0 +1,30 @@
+#include <iostream>
+
+int power(int n, int e) {
+    if (n < 0 || e < 0) return -1;
+    else if (e > 0) return n * power(n, e - 1);
+    else return 1;
+}
+
+int main() {
+    int n, e;
+
+    std::cout << "Enter number: ";
+    std::cin >> n;
+    std::cout << "Enter exponent: ";
+    std::cin >> e;
+
+    std::cout << "Ans: " << power(n, e) << std::endl;
+    return 0;
+
+    /*
+     * Example:
+     *
+     *      5^4
+     *
+     *              5 * 5^3 =
+     *          5 * 5 * 5^2 =
+     *      5 * 5 * 5 * 5^1 =
+     *  5 * 5 * 5 * 5 * 5^0 = 625
+     */
+}