// Package q1545 implements a solution for https://leetcode.com/problems/find-kth-bit-in-nth-binary-string/
package q1545

var buf = make([]byte, 1<<20)
var bufLen = 1

func init() { buf[0] = '0' }

func generate() {
	buf[bufLen] = '1'
	newTail := bufLen * 2
	for i := range bufLen {
		switch buf[i] {
		case '0':
			buf[newTail-i] = '1'
		case '1':
			buf[newTail-i] = '0'
		}
	}
	bufLen = newTail + 1
}

func findKthBit(n, k int) byte {
	for bufLen < k {
		generate()
	}
	return buf[k-1]
}

var _ = findKthBit