779. K-th Symbol in Grammar

On the first row, we write a 0. Now in every subsequent row, we look at the previous row and replace each occurrence of 0 with 01, and each occurrence of 1 with 10.

Given row N and index K, return the K-th indexed symbol in row N. (The values of K are 1-indexed.) (1 indexed).

**Examples:**
Input: N = 1, K = 1
Output: 0

Input: N = 2, K = 1
Output: 0

Input: N = 2, K = 2
Output: 1

Input: N = 4, K = 5
Output: 1

Explanation:
row 1: 0
row 2: 01
row 3: 0110
row 4: 01101001

Note:

1. N will be an integer in the range [1, 30].
2. K will be an integer in the range [1, 2^(N-1)].

# @lc code=start
using LeetCode

function kth_grammar(N::Int, K::Int)
    res = false
    for i in 1:N
        iseven(K) && (res = !res)
        K = (K + 1) >> 1
    end
    res
end
# @lc code=end

kth_grammar (generic function with 1 method)

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