chore: add Kaprekar number (#247)

algorithms/CPlusPlus/Maths/Kaprekar-number.cpp

@@ -0,0 +1,89 @@
+/* Program to find whether a number is kaprekar or not */
+
+#include<iostream>
+class Kaprekar
+{
+    // number private member variable
+    int number;
+public:
+    //constructor to initialize n in number
+    Kaprekar(int n)
+    {
+        number=n;
+    }
+
+// Function to calculate the total number of digits in the number.
+int total_digits()
+{
+    int total_count=0,copy=number;
+    //until the copy is not equal to 0 run the loop
+    while(copy)
+    {
+        //divide copy by 10 and assign it to copy
+        copy=copy/10;
+        //increment total_count by 1
+        total_count++;
+    }
+return total_count;
+}
+//Function to check whether the number is Kaprekar or not.
+int is_kaprekar(int total_count,int square,int number)
+{
+int i=0,arr[total_count],left=0,right=0,copy=square;
+//until copy is not equal to 0 run loop
+while(copy!=0)
+{
+    // assign copy%10 in arr[i]
+ arr[i]=copy%10;
+  //divide copy by 10 and assign it to copy
+  copy=copy/10;
+  //increment i by 1
+  i++;
+}
+/* assign total_count-1 in i and until i is greater and equal to
+total_count-(total_count/2) run the loop and decrement i by 1 */
+for(i=total_count-1;i>=total_count-(total_count/2);i--)
+{
+   //assign left*10+arr[i] in left
+   left=left*10+arr[i];
+}
+//now until i is not equal to 0 run the loop
+while(i>=0)
+{
+// assign right*10+arr[i] in right
+right=right*10+arr[i];
+// decrement i by 1
+i--;
+}
+// checking whether the left+right sum is equal to number
+if(left+right==number)
+    return 1;
+else
+    return 0;
+}
+};
+//driver code
+int main(int argc,char *argv[])
+{
+    int number,total_count,result,square;
+    std::cout<<"Enter a number: ";
+    //taking input in number
+    std::cin>>number;
+    square=number*number;
+    Kaprekar k(square);
+    //calling function k.total_digit() to get the total digit of number
+    total_count=k.total_digits();
+    //calling is_kaprekar function to check whether the number is kaprekar or not
+    result=k.is_kaprekar(total_count,square,number);
+    //printing the result which contain 1(kaprekar) or 0(not Kaprekar)
+    if(result)
+        std::cout<<number<<" is a kaprekar number"<< std::endl;
+    else
+        std::cout<<number<<" is not a kaprekar number"<< std::endl;
+    return 0;
+
+}
+/*
+Input: Enter a number: 9
+Output:9 is a kaprekar number
+*/

algorithms/CPlusPlus/README.md

@@ -57,3 +57,5 @@
 3. [Level Order Traversal](Trees/level-order-traversal.cpp)
 4. [Depth first Traversal](Trees/pre-in-post-traversal.cpp)
 
+# Maths
+1. [Kaprekar Number](Maths/Kaprekar-number.cpp)