hdu 5929 Basic Data Structure

ゲート

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;
}