//Describe how you could use a single array to implement three stacks.

package edu.java.chap3;

public class ThreeStack {

public static void change(int[] arr){

arr[0]=1;

}

public static void method1(){

int[] arr = new int[20];

//int[] ar1 = Arrays.copyOfRange(arr, 0, arr.length/3);

//System.out.println(ar1.length);

//int[] ar2 = Arrays.copyOfRange(arr,arr.length/3,arr.length/3+arr.length/3);

//int[] ar3 = Arrays.copyOfRange(arr,arr.length/3+arr.length/3,arr.length);

//System.out.println(ar3.length);

stack st1 = new stack(arr,0,arr.length/3-1);

stack st2 = new stack(arr,arr.length/3,2*arr.length/3-1);

stack st3 = new stack(arr,2*arr.length/3,arr.length);

st1.push(1);

st2.push(3);

st3.push(4);

System.out.println(st1.pop());

System.out.println(st1.pop());

for(int i = 0; i<arr.length;i++){

System.out.print(arr[i]);

}

}

public static void main(String[] args) {

method1();

/*System.out.println(arr[0]);

change(arr);

System.out.println(arr[0]);

stack st = new stack(arr);

System.out.println(st.arr[0]);

st.set();

System.out.println(st.arr[0]);

System.out.println(arr[0]);

*/

}

}

class stack{

public int[] arr;

public int pos;

public int start;

public int end;

public stack(int[] arr,int start,int end){

this.arr = arr;

this.pos = start;

this.start = start;

this.end = end;

}

//test the reference of arr is passed into the class

public void set(){

this.arr[0] = 2;

}

public void push(int x){

if(pos<=end){

this.arr[this.pos] = x;

this.pos++;

}

else{

System.out.println("this stack is full, try others");

}

}

public int pop(){

if(pos>start){

int result = this.arr[this.pos-1];

this.pos--;

return result;

} else {

System.out.println("this stack is empty");

return 0;

}

}

}