分析：
这题看出来的地方就是这个NAND是左结合的，不适用结合律，交换律。
所以想每次维护答案就不怎么可能了。比赛的时候一开始看成了异或，重读一遍题目了以后就一直去想了怎么维护答案。。。。。。
但是很容易看出来0是置1， 1是取反。于是维护一下最左边以及最右边的0的位置就可以了。要注意一下特殊情况，只有一个0是0，只有一个1是1。
剩下的就是用一个数组模拟栈，细节情况有点多，需要考虑很仔细才能通过。
代码：
/*****************************************************/
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <map>
#include <set>
#include <ctime>
#include <stack>
#include <queue>
#include <cmath>
#include <string>
#include <vector>
#include <cstdio>
#include <cctype>
#include <cstring>
#include <sstream>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
#define offcin ios::sync_with_stdio(false)
#define sigma_size 26
#define lson l,m,v<<1
#define rson m+1,r,v<<1|1
#define slch v<<1
#define srch v<<1|1
#define sgetmid int m = (l+r)>>1
#define LL long long
#define ull unsigned long long
#define mem(x,v) memset(x,v,sizeof(x))
#define lowbit(x) (x&-x)
#define bits(a) __builtin_popcount(a)
#define mk make_pair
#define pb push_back
#define fi first
#define se second
const int INF = 0x3f3f3f3f;
const LL INFF = 1e18;
const double pi = acos(-1.0);
const double inf = 1e18;
const double eps = 1e-9;
const LL mod = 1e9+7;
const int maxmat = 10;
const ull BASE = 31;
/*****************************************************/
const int maxn = 2e5 + 5;
int a[maxn << 1];
int z[maxn << 1];
int top, bot, topz, botz;
bool flag = true;
void Debug() {
if (flag) {
for (int i = top + 1; i <= bot; i ++)
cout<<a[i]<<" ";
puts("");
for (int i = topz + 1; i <= botz; i ++)
cout<<z[i]<<" ";
puts("");
}
else {
for (int i = top - 1; i >= bot; i --)
cout<<a[i]<<" ";
puts("");
for (int i = topz - 1; i >= botz; i --)
cout<<z[i]<<" ";
puts("");
}
}
int main(int argc, char const *argv[]) {
int T;
cin>>T;
for (int kase = 1; kase <= T; kase ++) {
int N; scanf("%d", &N);
top = topz = bot = botz = maxn;
mem(a, -1); mem(z, 0);
printf("Case #%d:\n", kase);
for (int i = 0; i < N; i ++) {
char op[10]; scanf("%s", op);
int x;
if (op[0] == 'P' && op[1] == 'U') {
scanf("%d", &x);
if (flag) {
a[top --] = x;
if (!x) z[topz --] = top + 1;
}
else {
a[top ++] = x;
if (!x) z[topz ++] = top - 1;
}
}
else if (op[0] == 'P' && op[1] == 'O') {
if (flag) {
top ++;
if (!a[top]) topz ++;
}
else {
top --;
if (!a[top]) topz --;
}
}
else if (op[0] == 'R') {
top += (flag ? 1 : -1);
topz += (flag ? 1 : -1);
swap(top, bot);
swap(topz, botz);
flag ^= 1;
top += (flag ? -1 : 1);
topz += (flag ? -1 : 1);
}
else {
if (top == bot) {puts("Invalid."); continue; }
else if (topz == botz) {
int num = abs(top - bot);
// cout<<"num1 "<<num<<endl;
printf("%d\n", (num & 1 ? 1 : 0));
continue;
}
else {
int ans = (abs(top - z[botz]) == 1 ? 0 : 1);
// cout<<"nums before 0"<<abs(top - z[botz])<<endl;
int num = abs(z[botz] - bot);
// cout<<"num1 "<<ans<<" "<<num<<endl;
if (num & 1) ans ^= 1;
printf("%d\n", ans);
continue;
}
}
// Debug();
}
}
return 0;
}