117 lines
1.9 KiB
Go
117 lines
1.9 KiB
Go
package wordsearchii
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type State struct {
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X, Y int
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Previous *State
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}
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func (s *State) Visited(x, y int) bool {
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if s == nil {
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return false
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}
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if s.X == x && s.Y == y {
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return true
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}
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return s.Previous.Visited(x, y)
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}
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type Trie struct {
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Children map[byte]*Trie
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States []*State
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}
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func NewTrie(board [][]byte) *Trie {
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trie := &Trie{
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Children: map[byte]*Trie{},
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States: []*State{},
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}
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for x := range board {
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for y := range board[x] {
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if _, ok := trie.Children[board[x][y]]; !ok {
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trie.Children[board[x][y]] = &Trie{
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Children: map[byte]*Trie{},
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States: []*State{},
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}
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}
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trie.Children[board[x][y]].States = append(trie.Children[board[x][y]].States, &State{
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X: x,
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Y: y,
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Previous: nil,
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})
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}
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}
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return trie
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}
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var CardinalDirections = [][2]int{
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{-1, 0},
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{1, 0},
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{0, -1},
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{0, 1},
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}
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func (t *Trie) Explore(board [][]byte, ch byte) *Trie {
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child := &Trie{
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Children: map[byte]*Trie{},
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States: []*State{},
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}
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for _, state := range t.States {
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for _, direction := range CardinalDirections {
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xNew, yNew := state.X+direction[0], state.Y+direction[1]
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if xNew < 0 || xNew >= len(board) || yNew < 0 || yNew >= len(board[xNew]) {
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continue
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}
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if state.Visited(xNew, yNew) {
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continue
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}
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if ch != board[xNew][yNew] {
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continue
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}
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child.States = append(child.States, &State{
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X: xNew,
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Y: yNew,
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Previous: state,
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})
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}
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}
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t.Children[ch] = child
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return child
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}
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func (t *Trie) FindWord(board [][]byte, word string) bool {
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if len(word) == 0 {
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return len(t.States) > 0
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}
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child, ok := t.Children[word[0]]
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if !ok {
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child = t.Explore(board, word[0])
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}
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return child.FindWord(board, word[1:])
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}
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func FindWords(board [][]byte, words []string) []string {
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trie := NewTrie(board)
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found := []string{}
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for _, word := range words {
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if trie.FindWord(board, word) {
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found = append(found, word)
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}
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}
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return found
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}
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