421B multithread.cpp

#include <cstdio>
#include <iostream>
#include <cstring>
#include <cmath>
#include <ctime>
#include <vector>
#include <string>
#include <algorithm>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <queue>
#include <deque>
#include <stack>
#include <numeric>
#include <memory>
#include <thread>
#include <future>

using namespace std;

#define PB                  push_back
#define F                   first
#define S                   second

#define REP(i,from,to)      for(auto i=(from); i<=(to); ++i)
#define PER(i,from,to)      for(auto i=(from); i>=(to); --i)
#define REP_IF(i,from,to,assert)   for(auto i=(from); i<=(to); ++i) if (assert)

#define FOR(i,less_than)    for (auto i=0; i<(less_than); ++i)
#define FORI(i, container)  for (auto i=0; i<(container).size(); ++i)
#define FORI_IF(i, container, assert) for (auto i=0; i<(container).size(); ++i) if (assert)
#define ROFI(i, container)  for (auto i=(container).size()-1; i>=0; --i)

#define FOREACH(elem, container)  for (auto elem : (container))
#define FILL(container, value)    memset(container, value, sizeof(container))
#define ALL(container)            (container).begin(), (container).end()
#define SZ(container)             (int)((container).size())

#define BACK(set_map)       *prev((set_map).end(), 1)
#define FRONT(set_map)      *(set_map).begin()

inline void _RD(int &x) { scanf("%d", &x); }
inline void _RD(long long &x) { scanf("%lld", &x); }
inline void _RD(double &x) { scanf("%lf", &x); }
inline void _RD(long double &x) { scanf("%Lf", &x); }
inline void _RD(char &x) { scanf(" %c", &x); }
inline void RD() {}
template<class T, class... U> 
inline void RD(T &head, U &... tail) { _RD(head); RD(tail...); }

using PII = pair<int,int>;
using LL  = long long;
using VI  = vector<int>;
using VLL = vector<LL>;
using VVI = vector<VI>;

unordered_set<char> st = {'A','H','I','M','O','T','U','V','W','X','Y'};

bool f(const string& S, int s, int e) {
    for (int i=s; i<=e; ++i) {
        int j = SZ(S)-i-1;
        if (!(S[i]==S[j] && st.find(S[i])!=st.end())) 
            return false;
    }
    return true;
}

int main() {    
    string s;
    cin >> s;
    bool valid = true;
    // 0..n/2
    future<bool> f1 = async(launch::async, f, cref(s), 0, SZ(s)/4);
    future<bool> f2 = async(launch::async, f, cref(s), SZ(s)/4, SZ(s)/2);


    if (f1.get() && f2.get()) printf("YES\n"); else printf("NO\n");

    return 0;
}