HDU 5929 Basic Data Structure（模拟 + 乱搞）题解

#include<set>
#include<map>
#include<stack>
#include<cmath>
#include<queue>
#include<vector>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
typedef long long ll;
using namespace std;
const int maxn = 200000 + 100;
const int seed = 131;
const ll MOD = 109;
const int INF = 0x3f3f3f3f;
deque<int> q;   //0
int main(){
    int t, x, l, r, ca = 1, cnt;
    char order[10];
    scanf("%d", &t);
    while(t--){
        printf("Case #%d:\n", ca++);
        int n;
        int turn = 1;
        cnt = 0;
        l = 0, r = -1;
        while(!q.empty()) q.pop_back();
        scanf("%d", &n);
        while(n--){
            scanf("%s", order);
            if(order[2] == ‘S‘){    //push
                scanf("%d", &x);
                if(turn){
                    cnt++;
                    r++;
                    if(x == 0) q.push_back(r);
                }
                else{
                    cnt++;
                    l--;
                    if(x == 0) q.push_front(l);
                }
            }
            else if(order[2] == ‘P‘){   //pop
                if(turn){
                    if(!q.empty() && q.back() == r) q.pop_back();
                    r--;
                }
                else{
                    if(!q.empty() && q.front() == l) q.pop_front();
                    l++;
                }
                cnt--;
            }
            else if(order[2] == ‘V‘){   //reverse
                turn ^= 1;
            }
            else{   //query
                int ans;
                if(cnt == 0) printf("Invalid.\n");
                else{
                    if(q.empty()) ans = (r - l + 1) % 2;
                    else{
                        if(turn)
                            ans = (q.front() - l + 1 - (q.front() == r)) % 2;
                        else
                            ans = (r - q.back() + 1 - (q.back() == l)) % 2;
                    }
                    printf("%d\n", ans);
                }
            }
        }
    }
    return 0;
}