Function exist

word_search_79/solution.go:9–19

Time: O(N * 4^(L (len of word))) Space: O(L) recursion stack at most L

(board [][]byte, word string)

// Time: O(N * 4^(L (len of word)))
// Space: O(L) recursion stack at most L
func exist(board [][]byte, word string) bool {
	for r := 0; r < len(board); r++ {
		for c := 0; c < len(board[r]); c++ {
			if word[0] == board[r][c] && explore(board, word, 0, r, c) {
				return true
			}
		}
	}

	return false
}

func explore(board [][]byte, word string, step, r, c int) bool {
	// if the step is equal to the length of word, then word exists