From e42f4bb0b1e7f7b7413e95038eb8f9aac997e45e Mon Sep 17 00:00:00 2001
From: Ashad <93534298+Ashad001@users.noreply.github.com>
Date: Thu, 11 Aug 2022 23:52:36 +0500
Subject: [PATCH] chore(CPlusPlus): add reverse number algorithm (#789)

Co-authored-by: Arsenic <54987647+Arsenic-ATG@users.noreply.github.com>
---
 algorithms/C/maths/fibonacci-number/src/fib.c |  2 +-
 algorithms/C/maths/fibonacci-number/src/fib.h |  7 ++--
 .../C/maths/fibonacci-number/src/main.c       |  2 +-
 algorithms/CPlusPlus/README.md                |  1 +
 .../CPlusPlus/Recursion/reverse-a-number.cpp  | 34 +++++++++++++++++++
 5 files changed, 41 insertions(+), 5 deletions(-)
 create mode 100644 algorithms/CPlusPlus/Recursion/reverse-a-number.cpp

diff --git a/algorithms/C/maths/fibonacci-number/src/fib.c b/algorithms/C/maths/fibonacci-number/src/fib.c
index 41196239..25ead35d 100644
--- a/algorithms/C/maths/fibonacci-number/src/fib.c
+++ b/algorithms/C/maths/fibonacci-number/src/fib.c
@@ -1,4 +1,4 @@
-#include"fib.h"
+#include"./fib.h" // NOLINT(build/include)
 #include<math.h> // sqrt, pow are used in binet_fib
 
 int recur_fib(int n){
diff --git a/algorithms/C/maths/fibonacci-number/src/fib.h b/algorithms/C/maths/fibonacci-number/src/fib.h
index c770d96d..febadaf1 100644
--- a/algorithms/C/maths/fibonacci-number/src/fib.h
+++ b/algorithms/C/maths/fibonacci-number/src/fib.h
@@ -1,5 +1,6 @@
-#ifndef FIB_H_INCLUDED
-#define FIB_H_INCLUDED
+
+#ifndef ALGORITHMS_C_MATHS_FIBONACCI_NUMBER_SRC_FIB_H_
+#define ALGORITHMS_C_MATHS_FIBONACCI_NUMBER_SRC_FIB_H_
 
 /**
  * fib(n) takes nonnegative number n
@@ -19,4 +20,4 @@ int iter_log_fib(int n);
 int log_fib(int n);
 int binet_fib(int n);
 
-#endif
\ No newline at end of file
+#endif  // ALGORITHMS_C_MATHS_FIBONACCI_NUMBER_SRC_FIB_H_"
diff --git a/algorithms/C/maths/fibonacci-number/src/main.c b/algorithms/C/maths/fibonacci-number/src/main.c
index 8bc173fc..7e0759db 100644
--- a/algorithms/C/maths/fibonacci-number/src/main.c
+++ b/algorithms/C/maths/fibonacci-number/src/main.c
@@ -1,5 +1,5 @@
 #include<stdio.h>
-#include"fib.h"
+#include"./fib.h" // NOLINT(build/include)
 
 int main(){
 	memomizing_fib(); // this is to initialize the memomized table
diff --git a/algorithms/CPlusPlus/README.md b/algorithms/CPlusPlus/README.md
index c545fa88..0350073e 100644
--- a/algorithms/CPlusPlus/README.md
+++ b/algorithms/CPlusPlus/README.md
@@ -186,6 +186,7 @@
 - [Product of two numbers](Recursion\product-of-numbers.cpp)
 - [Product of digits in a number](Recursion\product-of-digits.cpp)
 - [Linear search using recursion](Recursion/linear-search.cpp)
+- [Reverse a number using recursion](Recursion/reverse-a-number.cpp)
 
 ## Number System
 
diff --git a/algorithms/CPlusPlus/Recursion/reverse-a-number.cpp b/algorithms/CPlusPlus/Recursion/reverse-a-number.cpp
new file mode 100644
index 00000000..884402bc
--- /dev/null
+++ b/algorithms/CPlusPlus/Recursion/reverse-a-number.cpp
@@ -0,0 +1,34 @@
+/*
+Description: Program to reverse integer using recursion
+Time complexity: O(n) where n is the number of digits in the integer
+*/
+
+#include <cmath>
+#include <iostream>
+using namespace std;
+
+int Helper(int n ,int base , int ans)
+{
+    if(n < 1)
+        return ans;
+    ans = ans * base + (n % 10);    // Update the ans for every digit
+    return Helper(n / 10, base , ans);    
+}
+
+int Rev(int n)
+{
+    return Helper(n , 10, 0);
+}
+
+
+int main(int argc, char const *argv[])
+{   
+    cout << Rev(13579);
+
+    return 0;
+}
+/*
+Input: 13579
+Output: 97531
+*/
+