KapreKar.java

KapreKar.java

@@ -0,0 +1,54 @@
+// Java program to check if a number is  
+// Kaprekar number or not 
+
+class KapreKar
+{ 
+    // Returns true if n is a Kaprekar number, else false 
+    static boolean iskaprekar(int n) 
+    { 
+        if (n == 1) 
+           return true; 
+
+        // Count number of digits in square 
+        int sq_n = n * n; 
+        int count_digits = 0; 
+        while (sq_n != 0) 
+        { 
+            count_digits++; 
+            sq_n /= 10; 
+        } 
+
+        sq_n = n*n; // Recompute square as it was changed 
+
+        // Split the square at different poitns and see if sum 
+        // of any pair of splitted numbers is equal to n. 
+        for (int r_digits=1; r_digits<count_digits; r_digits++) 
+        { 
+             int eq_parts = (int) Math.pow(10, r_digits); 
+
+             // To avoid numbers like 10, 100, 1000 (These are not 
+             // Karprekar numbers 
+             if (eq_parts == n) 
+                continue; 
+
+             // Find sum of current parts and compare with n 
+             int sum = sq_n/eq_parts + sq_n % eq_parts; 
+             if (sum == n) 
+               return true; 
+        } 
+
+        // compare with original number 
+        return false; 
+    } 
+
+    // Driver method 
+    public static void main (String[] args) 
+    { 
+        System.out.println("Printing first few Kaprekar Numbers" + 
+                             " using iskaprekar()"); 
+
+        for (int i=1; i<10000; i++) 
+            if (iskaprekar(i)) 
+                 System.out.print(i + " "); 
+    } 
+}