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Java-based LeetCode algorithm problem solutions, regularly updated
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package g0201_0300.s0212_word_search_ii;
// #Hard #Top_Interview_Questions #Array #String #Matrix #Backtracking #Trie
// #2022_07_02_Time_21_ms_(99.42%)_Space_44.1_MB_(67.33%)
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class Solution {
private Tree root;
public List findWords(char[][] board, String[] words) {
if (board.length < 1 || board[0].length < 1) {
return Collections.emptyList();
}
root = new Tree();
for (String word : words) {
Tree.addWord(root, word);
}
List collected = new ArrayList<>();
for (int i = 0; i != board.length; ++i) {
for (int j = 0; j != board[0].length; ++j) {
dfs(board, i, j, root, collected);
}
}
return collected;
}
private void dfs(char[][] board, int i, int j, Tree cur, List collected) {
char c = board[i][j];
if (c == '-') {
return;
}
cur = cur.getChild(c);
if (cur == null) {
return;
}
if (cur.end != null) {
String s = cur.end;
collected.add(s);
cur.end = null;
if (cur.len() == 0) {
Tree.deleteWord(root, s);
}
}
board[i][j] = '-';
if (i > 0) {
dfs(board, i - 1, j, cur, collected);
}
if (i + 1 < board.length) {
dfs(board, i + 1, j, cur, collected);
}
if (j > 0) {
dfs(board, i, j - 1, cur, collected);
}
if (j + 1 < board[0].length) {
dfs(board, i, j + 1, cur, collected);
}
board[i][j] = c;
}
}
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