Create 212-word-search-ii.js

Author: everthis

212-word-search-ii.js

@@ -0,0 +1,56 @@
+/**
+ * @param {character[][]} board
+ * @param {string[]} words
+ * @return {string[]}
+ */
+class Trie {
+  constructor() {
+    this.word = null
+    this.children = new Map()
+  }
+  add(word) {
+    let cur = this
+    for (let i = 0; i < word.length; i++) {
+      if (!cur.children.has(word[i])) {
+        cur.children.set(word[i], new Trie())
+      }
+      cur = cur.children.get(word[i])
+    }
+    cur.word = word
+  }
+  addArr(words) {
+    words.forEach(word => this.add(word))
+  }
+}
+
+const findWords = function(board, words) {
+  const trie = new Trie()
+  trie.addArr(words)
+  const results = []
+  const dirs = [[-1, 0], [1, 0], [0, 1], [0, -1]]
+  for (let i = 0; i < board.length; i++) {
+    for (let j = 0; j < board[0].length; j++) {
+      dfs(board, i, j, trie, results, dirs)
+    }
+  }
+  return results
+}
+
+const dfs = (board, i, j, trie, results, dirs) => {
+  if(i < 0 || j < 0 || i >= board.length || j >= board[0].length) return
+  const char = board[i][j]
+  if (!trie.children.has(char)) return
+
+  const nextTrie = trie.children.get(char)
+  if (nextTrie.word) {
+    results.push(nextTrie.word)
+    nextTrie.word = null
+  }
+  
+  for(let dir of dirs) {
+    board[i][j] = '#'
+    dfs(board, i + dir[0], j + dir[1], nextTrie, results, dirs)
+    board[i][j] = char
+  }
+  
+}