[Luogu] 时间复杂度

https://www.luogu.org/problemnew/show/P3952

考场上输出的是 "YES" "NO"

++ ，如果不是亲身经历，打死我我都不信

思路：

　　递归模拟

　　细节挺多

　　难度不大

　　容易写挂

#include <bits/stdc++.h>

using namespace std;
const int oo = ;

int T, L, Maxpow;
char use[];
bool vis[], flag;
int last;

inline int get() {
    char c[];
    scanf("%s", c);
    int len = strlen(c);
    int ret = ;
    if(len == ) return c[] == 'n' ? oo : c[] - '';
    else for(int i = ; i < len; i ++) ret = ret *  + c[i] - '';
    return ret;
}

void Go_on() {
    int jsF(), jsE();
    while(jsE <= jsF) {
        L --;
        char H; cin >> H;
        if(H == 'E') {jsE ++; vis[use[last --]] = ; if(jsE > jsF) return ;}
        else {
            char Int; int x, y;
            cin >> Int; x = get(); y = get();
            if(vis[Int]) {flag = ; return ;}
            else {vis[Int] = ; use[++ last] = Int;}
            jsF ++;
        }
    }
}

void Work(int floor_pow, int floor) { // 到达当前层时的最大次数
    while(L) {
        if(flag) return ;
        L --;
        char H; cin >> H;
        if(H == 'F') {
            char Int; cin >> Int; int x = get(), y = get();
            if(vis[Int]) {flag = ; return ;}
            else {vis[Int] = ; use[++ last] = Int;}
            if(x != oo && y == oo) {
                Maxpow = max(Maxpow, floor_pow + );
                Work(floor_pow + , floor + );
            } else {
                if((x == oo && y != oo) || (x > y)) {Go_on();}
                else Work(floor_pow, floor + );
            }
        } else {
            vis[use[last --]] = ;
            if(floor != ) return ;
        }
    }

}

inline void Read_over() {
    while(L) {L --; char H; cin >> H; if(H == 'F') {cin >> H; H = get(); H = get();}}
}

int main() {
    cin >> T;
    while(T --) {
        cin >> L;
        char tim[];
        scanf("%s", tim);
        memset(vis, , sizeof vis); last = ;
        int len = strlen(tim);
        if(L % ) {cout << "ERR" << endl; Read_over(); continue ;}
        Maxpow = ; last = ; flag = ;
        Work(, );
        if(L) Read_over();
        if(last || flag) {cout << "ERR" << endl; continue ;}
        int Pow;
        if(tim[] == '') Pow = ;
        else if(len == ) Pow = tim[] - '';
        else if(len == ) Pow = (tim[] - '') *  + tim[] - '';
        else if(len == ) Pow = ((tim[] - '') *  + tim[] - '') *  + tim[] - '';
        if(Pow == Maxpow) cout << "Yes" << endl;
        else cout << "No" << endl;
    }
    return ;
}