Create inverse_of_number.java

inverse_of_number.java

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+/*  QUESTION:
+1. The key constraint is if the number is 5 digits long, it'll contain all the digits from 1 to 5 without missing any and without repeating 
+any. e.g. 23415 is a 5 digit long number containing all digits from 1 to 5 without missing and repeating any digit from 1 to 5.Take a look at few other valid numbers
+- 624135, 81456273 etc.Here are a few invalid numbers - 139, 7421357 etc.
+2. The inverse of a number is defined as the number created by interchanging the face value and index of digits of number.e.g. for 426135 (reading from right to left, 
+5 is in place 1, 3 is in place 2, 1 is in place 3, 6 is in place 4, 2 is in place 5 and 4 is in place 6), the inverse will be 416253 (reading from right to left, 3 is 
+in place 1, 5 is in place 2,2 is in place 3, 6 is in place 4, 1 is in place 5 and 4 is in place 6) More examples - inverse of 2134 is 1243 and inverse of 24153 is 24153    
+3. Take as input number "n", assume that the number will follow constraints.
+4. Print it's inverse.*/
+// input=28346751
+// output=73425681
+
+import java.util.*;
+
+public class Main{
+
+public static void main(String[] args) {
+
+  Scanner scn  = new Scanner(System.in);
+  int n = scn.nextInt();
+  int sum=0, count=0,temp;
+  while(n > 0)
+  {
+      temp = n%10;
+      count++;
+      sum = sum + (count * (int)(Math.pow(10,temp-1))); 
+      n = n/10;
+  }
+  System.out.println(sum);
+ }
+}

prime_numbers_in_given_range.java

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+// taking low and high as inputs and displaying all prime numbers >=low and <=high
+import java.util.*;
+
+public class Main{
+    public static void main(String[] args) {
+        // write your code here
+        Scanner scn = new Scanner(System.in);
+
+       // write ur code here
+       int low = scn.nextInt();
+       int high = scn.nextInt();
+       for(int i=low; i<=high; i++)
+       {
+
+           int count=0;
+
+           for(int j=2; (j*j)<=i; j++) // (j*j)<=i is used because if that's possible then it will have 
+                                       //atleast one divisor till sqrt(i)
+           {
+
+               if(i%j == 0 && i!=2)
+               {
+                   count++;
+                   break;
+               }
+           }
+           if(count == 0)
+           {
+               System.out.println(i);
+           }
+       }
+
+    }
+}

rotate_a_number.java

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+/*question: 1. You are given two numbers n and k. You are required to rotate n, k times to the right. If k is positive, rotate to the right i.e. remove rightmost digit and make it leftmost. Do the reverse for negative value of k. Also k can have an absolute value larger than number of digits in n.
+            2. Take as input n and k.
+            3. Print the rotated number.
+            4. Note - Assume that the number of rotations will not cause leading 0's in the result. e.g. such an input will not be given
+               n = 12340056
+               k = 3
+               r = 05612340 */
+import java.util.*;
+
+   public class Main{
+
+   public static void main(String[] args) {
+
+     Scanner scn = new Scanner(System.in);
+     int n = scn.nextInt();
+     int k = scn.nextInt();
+     int temp,count=0,temp1;
+     temp1 = n;
+     // -->condition 1: for k less than number of digits and positive, exactly k number of digits will come forward and rest array will shift backwards
+     // eg: n=543689 and k=2
+     // rotation no. 1: 954368 rotation no. 2: [89]5436 -> k digits came in front and rest array shifted
+     while(temp1 > 0) 
+     {
+        temp1 = temp1 / 10;
+        count++;
+     }
+     if(k > 0)
+     {
+         k = k % count;
+         if(k == 0)
+         {
+             k = count;//after k=no. of digits repetations, we get actual number back
+         }
+     }
+     else //if k is less than 0 
+     {
+         if(k == 0) k=count; 
+         else 
+         {
+             k = (-k) % count;
+             k = count - k;// negative k is equivalent to (count-k) value of positive k 
+         }
+     }
+     // code described below is to shift required digits in front and shift rest array rightwards
+     temp = n % ((int) Math.pow(10,k));
+     n = n - temp;
+     n  = n / ((int)Math.pow(10,k));
+     n = n + (temp * ((int ) Math.pow(10,count-k)));
+     System.out.println(n);
+    }
+   }