HDU 4286 Data Handler --双端队列

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <queue>
using namespace std;
#define N 500007

deque<int> LE,MI,RI;
deque<int>::iterator it;
int fir,revd,a[N];

int pop_Back(deque<int>& d)
{
    int now = d.back();
    d.pop_back();
    return now;
}

int pop_Front(deque<int>& d)
{
    int now = d.front();
    d.pop_front();
    return now;
}

void out()
{
    if(fir){ printf("%d",*it); fir = 0; }
    else printf(" %d",*it);
}

void print()
{
    fir = 1;
    for(it=LE.begin();it!=LE.end();it++)
        out();
    if(revd)
    {
        for(it=MI.end()-1;it!=MI.begin()-1;it--)
            out();
    }
    else
    {
        for(it=MI.begin();it!=MI.end();it++)
            out();
    }
    for(it=RI.begin();it!=RI.end();it++)
        out();
    puts("");
}

int main()
{
    int t,n,x,i,l,r,m;
    char ss1[15],ss2[3];
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(i=1;i<=n;i++)
            scanf("%d",&a[i]);
        scanf("%d%d%d",&l,&r,&m);
        LE.clear(), MI.clear(), RI.clear();
        for(i=1;i<l;i++) LE.push_back(a[i]);
        for(i=l;i<=r;i++) MI.push_back(a[i]);
        for(i=r+1;i<=n;i++) RI.push_back(a[i]);
        revd = 0;
        while(m--)
        {
            scanf("%s",ss1);
            if(ss1[0] == ‘R‘)
                revd ^= 1;
            else if(ss1[0] == ‘M‘)
            {
                scanf("%s",ss2);
                if(ss1[4] == ‘L‘)   //MoveLeft
                {
                    if(ss2[0] == ‘L‘)   //point L MoveLeft
                    {
                        x = pop_Back(LE);
                        if(revd) MI.push_back(x);
                        else     MI.push_front(x);
                    }
                    else                //point R MoveLeft
                    {
                        if(revd) x = pop_Front(MI);
                        else     x = pop_Back(MI);
                        RI.push_front(x);
                    }
                }
                else                //MoveRight
                {
                    if(ss2[0] == ‘L‘)   //point L MoveRight
                    {

                        if(revd) x = pop_Back(MI);
                        else     x = pop_Front(MI);
                        LE.push_back(x);
                    }
                    else                //point R MoveRight
                    {
                        x = pop_Front(RI);
                        if(revd) MI.push_front(x);
                        else     MI.push_back(x);
                    }
                }
            }
            else if(ss1[0] == ‘I‘)
            {
                scanf("%s%d",ss2,&x);
                if(ss2[0] == ‘L‘)
                {
                    if(revd) MI.push_back(x);
                    else     MI.push_front(x);
                }
                else
                {
                    if(!revd) MI.push_back(x);
                    else     MI.push_front(x);
                }
            }
            else if(ss1[0] == ‘D‘)
            {
                scanf("%s",ss2);
                if(ss2[0] == ‘L‘)
                {
                    if(revd) pop_Back(MI);
                    else     pop_Front(MI);
                }
                else
                {
                    if(!revd) pop_Back(MI);
                    else     pop_Front(MI);
                }
            }
        }
        print();
    }
    return 0;
}