779. K-th Symbol in Grammar

gistfile1.txt

class Solution {
public:
    int kthGrammar(int N, int K) {
        
        if (N == 1 && K == 1) return 0;
        if (K % 2) {
            return kthGrammar(N - 1, (K + 1) / 2) ? 1 : 0;
        } else {
            return kthGrammar(N - 1, (K + 1) / 2) ? 0 : 1;
        }
        
        /*
        value: 0
        index: 1
        
        value: 01
        index: 1
        
        value: 01 10
        index:  2
        
        value: 01 10 10 01
        index:     4
        
        value: 01 10 10 01 10 01 01 10
        index:          78
        */
    }
};