Google interview question
Implement the stack structure and its functions (push, pop, empty)
Interview Answers
I used a vector (in c++) as the container for the stack. I also used template.
package interviewQuestions;
import java.util.ArrayList;
import java.util.List;
public class StackX> {
private List arr;
private int top;
public StackX()
{
top=-1;
arr=new ArrayList();
}
public void push(T item)
{
arr.add(item);
top++;
}
public boolean isEmpty()
{
return (top==0);
}
public T pop()
{
T cur=arr.get(top);
arr.remove(top);
top--;
return cur;
}
public T peek()
{
if(top>0)
return arr.get(top);
else
return null;
}
public static void main(String[] args) {
StackX s=new StackX();
s.push("ABC"); s.push("BBC"); s.push("CBC"); s.push("DBC");
System.out.println(s.isEmpty());
System.out.println(s.peek());
System.out.println(s.pop());
s.push("EBC");
System.out.println(s.pop());
}
}