// Use int array to implement Stack /** * Created by xiaoyaoworm on 4/16/16. */ public class Stack { int maxSize; int[] arr; int top; public Stack(int size){ maxSize = size; arr = new int[size]; top = -1; } public void push(int num){ if(top == arr.length - 1){ System.out.println("Stack is full, cannot push."); } else { top++; arr[top] = num; } } public int pop(){ if(top == -1){ System.out.println("Stack is empty, cannot pop."); return -1; } else{ int res = arr[top]; arr[top] = 0; top--; return res; } } public boolean isEmpty(){ if(top == -1) return true; else return false; } public int peek(){ return arr[top]; } }