Add Tree Depth First Search/720_Longest_Word_in_Dictionary.java

Author: seanprashad

Tree Depth First Search/720_Longest_Word_in_Dictionary.java

@@ -0,0 +1,53 @@
+class Solution {
+    private TrieNode root = new TrieNode();
+    private String result = "";
+
+    public String longestWord(String[] words) {
+        for (String word : words) {
+            root.insert(word);
+        }
+
+        dfs(root);
+        return result;
+    }
+
+    private void dfs(TrieNode root) {
+        if (root == null) { return; }
+
+        if (root.word != null) {
+            if (root.word.length() > result.length()) {
+                result = root.word;
+            }
+        }
+
+        for (TrieNode child : root.children) {
+            if (child != null && child.word != null) {
+                dfs(child);
+            }
+        }
+    }
+
+    private class TrieNode {
+        private TrieNode[] children;
+        private String word;
+
+        public TrieNode() {
+            children = new TrieNode[26];
+            word = null;
+        }
+
+        public void insert(String word) {
+            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;
+        }
+    }
+}