Update 212_Word_Search_II.java

Author: seanprashad

Tree Depth First Search/212_Word_Search_II.java

@@ -1,67 +1,66 @@
 class Solution {
-    class TrieNode {
-        private TrieNode[] children;
-        private String word;
-
-        public TrieNode() {
-            children = new TrieNode[26];
-            word = null;
-        }
-    }
-
-    private TrieNode buildTrie(String[] words) {
-        TrieNode root = new TrieNode();
-
-        for (String word : words) {
-            TrieNode runner = root;
-
-            for (char c : word.toCharArray()) {
-                if (runner.children[c - 'a'] == null) {
-                    runner.children[c - 'a'] = new TrieNode();
-                }
-
-                runner = runner.children[c - 'a'];
-            }
-
-            runner.word = word;
-        }
-
-        return root;
-    }
-
     public List<String> findWords(char[][] board, String[] words) {
-        TrieNode root = buildTrie(words);
         List<String> result = new ArrayList<>();
+        TrieNode root = buildTrie(words);
 
-        for (int i = 0; i < board.length; i++) {
-            for (int j = 0; j < board[i].length; j++) {
-                helper(board, i, j, root, result);
+        for (int row = 0; row < board.length; row++) {
+            for (int col = 0; col < board[row].length; col++) {
+                dfs(board, row, col, root, result);
             }
         }
 
         return result;
     }
 
-    private void helper(char[][] board, int row, int col, TrieNode root, List<String> result) {
+    private void dfs(char[][] board, int row, int col, TrieNode root, List<String> result) {
         if (root.word != null) {
             result.add(root.word);
             root.word = null;
-            return;
         }
 
         if (row < 0 || col < 0 || row >= board.length || col >= board[row].length || board[row][col] == '.'
-                || root.children[board[row][col] - 'a'] == null) {
+                || root.letters[board[row][col] - 'a'] == null) {
             return;
         }
 
         char c = board[row][col];
         board[row][col] = '.';
 
-        helper(board, row + 1, col, root.children[c - 'a'], result);
-        helper(board, row - 1, col, root.children[c - 'a'], result);
-        helper(board, row, col + 1, root.children[c - 'a'], result);
-        helper(board, row, col - 1, root.children[c - 'a'], result);
+        dfs(board, row + 1, col, root.letters[c - 'a'], result);
+        dfs(board, row - 1, col, root.letters[c - 'a'], result);
+        dfs(board, row, col + 1, root.letters[c - 'a'], result);
+        dfs(board, row, col - 1, root.letters[c - 'a'], result);
 
         board[row][col] = c;
     }
+
+    private TrieNode buildTrie(String[] words) {
+        TrieNode root = new TrieNode();
+
+        for (String w : words) {
+            TrieNode runner = root;
+
+            for (char c : w.toCharArray()) {
+                if (runner.letters[c - 'a'] == null) {
+                    runner.letters[c - 'a'] = new TrieNode();
+                }
+
+                runner = runner.letters[c - 'a'];
+            }
+
+            runner.word = w;
+        }
+
+        return root;
+    }
+
+    private class TrieNode {
+        private TrieNode[] letters;
+        private String word;
+
+        public TrieNode() {
+            letters = new TrieNode[26];
+            word = null;
+        }
+    }
 }