word search ii solution

Author: yhkee0404

word-search-ii/yhkee0404.go

@@ -0,0 +1,62 @@
+func findWords(board [][]byte, words []string) []string {
+	root := &TrieNode{}
+	for _, w := range words {
+		root.Insert(w)
+	}
+
+	m, n := len(board), len(board[0])
+	results := []string{}
+
+	var dfs func(r, c int, node *TrieNode)
+	dfs = func(r, c int, node *TrieNode) {
+		ch := board[r][c]
+		if ch == '#' {
+			return
+		}
+		idx := ch - 'a'
+		next := node.children[idx]
+		if next == nil {
+			return
+		}
+		if next.word != "" {
+			results = append(results, next.word)
+			next.word = ""
+		}
+
+		board[r][c] = '#'
+		for _, d := range directions {
+			nr, nc := r+d[0], c+d[1]
+			if nr >= 0 && nr < m && nc >= 0 && nc < n {
+				dfs(nr, nc, next)
+			}
+		}
+		board[r][c] = ch
+	}
+
+	for i := 0; i < m; i++ {
+		for j := 0; j < n; j++ {
+			dfs(i, j, root)
+		}
+	}
+
+	return results
+}
+
+type TrieNode struct {
+	children [26]*TrieNode
+	word     string
+}
+
+func (t *TrieNode) Insert(word string) {
+	node := t
+	for _, ch := range word {
+		idx := ch - 'a'
+		if node.children[idx] == nil {
+			node.children[idx] = &TrieNode{}
+		}
+		node = node.children[idx]
+	}
+	node.word = word
+}
+
+var directions = [][]int{{0, 1}, {0, -1}, {1, 0}, {-1, 0}}