Implement_two_stacks_in_an_array.java

class twoStacks
{
    int arr[];
    int size;
    int top1, top2;
    twoStacks()
    {
        size = 100; 
        arr = new int[100]; 
        top1 = -1; 
        top2 = size;
    }
    //Function to push an integer into the stack1.
    void push1(int x)
    {
        if(top1>=top2) return;
        arr[++top1]=x;
     
    }
    //Function to push an integer into the stack2.
    void push2(int x)
    {
       if(top1>=top2) return;
       arr[--top2]=x;
    }
    //Function to remove an element from top of the stack1.
    int pop1()
    {
        if(top1==-1) return -1;
        return arr[top1--];
    }
    //Function to remove an element from top of the stack2.
    int pop2()
    {
        if(top2==size) return -1;
        return arr[top2++];
    }
}