Will keep on sharing Data Structure questions...

Below is one coding question asked around the knowledge of Data Structures.
Stacks, Queues, List, Set & Trees are the items against which you can be grilled by the interviewer along with the algorithms using these Data Structures. Here I will try to put some sample codes & you can also look the section - Coding Interviews

// Sort the stack of numbers using only one more stack
import java.util.Random;
import java.util.Stack;
public class StackSort {
 public static void main(String[] args) {
  Stack<Integer> stack1 = new Stack<>();
  int range = 1000000;
  Random random = new Random();
  for(int i = 0; i < range; i++) {
   stack1.push(random.nextInt(range));
  }
  long start = System.currentTimeMillis();
  sort(stack1);
  System.out.println("Time taken :- " + (System.currentTimeMillis()-start) + " ms");
 }
 public static void sort(Stack<Integer> stack1) {
     Stack<Integer> stack2 = new Stack<>();
     while(!stack1.isEmpty()) {
        int next = stack1.pop();
        while (!stack2.isEmpty() && next <= stack2.peek()) {
        stack1.push(stack2.pop());
      }
      stack2.push(next);
    }
    while(!stack2.isEmpty())
       stack1.push(stack2.pop());
  }
}​

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