TICKETS (Codechef parctice)

TICKETS5.cpp

#include <cstdio>
using namespace std;

bool dfa(){                             // Check what a DFA (Deterministic Finite Automaton) is and how it works.
    int state = 0;                      // DFAs are a bit complex for beginners, because it's an abstract mathematical
    char a = getchar();                 // concept. But on the other hand the logic used for this specific problem
    char b = getchar();                 // is very basic. Hence just the basic idea of the DFA concept should suffice.
    if(a==b) state = 2;
    char ch;
    while((ch=getchar()) != '\n'){
        if(state == 0){
            if(ch==a) state = 1;
            else state = 2;
        }
        else if(state == 1){
            if(ch==b) state = 0;
            else state = 2;
        }
    }
    return !(state == 2);
}

int main(){
    int T;
    bool res;
    scanf("%d\n",&T);
    while(T--){
        res = dfa();
        if(res) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}