What's so cool in this test? It pushes a lot into one stack or a lot into many stacks or what?
#include <iostream>
using namespace std;

struct elem
{
    unsigned int value;
    elem * next;
};
elem ** tree;
elem * push(elem * stack,unsigned int value)
{
    if(!stack)
    {
        stack = new elem;
        stack->value = value;
        stack->next = NULL;
        return stack;
    }
    else
    {
        elem * temp = new elem;
        temp->value = value;
        temp->next = stack;
        return temp;
    }
}
elem * pop(elem * stack,unsigned int & value)
{
    elem * temp = stack->next;
    value = stack->value;
    delete stack;
    return temp;
}
int main()
{
    tree = new elem* [1000];
    memset(tree,0,1000*4);
    int n;
    cin>>n;
    char str[5];
    int a;
    unsigned int b;
    for(int i = 0;i<n;++i)
    {
        cin>>str;
        if(str[1]=='U')
        {
            cin>>a;
            cin>>b;
            tree[a-1] = push(tree[a-1],b);

        }
        else
        {
            cin>>a;
            unsigned int value;
            tree[a-1] = pop(tree[a-1],value);
            cout<<value<<endl;

        }
    }

    return 0;
}

OMG. Changed iostream on stdio.h and it got accepted!! :) 713kb OMG OMG OMG