solved implement-trie-prefix-tree.

Author: sangbeenmoon

implement-trie-prefix-tree/sangbeenmoon.java

@@ -0,0 +1,57 @@
+import java.util.HashMap;
+import java.util.Map;
+
+class Trie {
+
+    Map<Character, Trie> map;
+    boolean isEnd = false;
+
+    public Trie() {
+        map = new HashMap<>();
+    }
+
+    public void insert(String word) {
+        Trie trie;
+        if (map.containsKey(word.charAt(0))) {
+            trie = map.get(word.charAt(0));
+        } else {
+            trie = new Trie();
+        }
+        map.put(word.charAt(0), trie);
+
+        if (word.length() == 1) {
+            map.get(word.charAt(0)).isEnd = true;
+            return;
+        }
+
+        trie.insert(word.substring(1));
+    }
+
+    public boolean search(String word) {
+        if (map.containsKey(word.charAt(0))) {
+            if (word.length() == 1) {
+                return map.get(word.charAt(0)).isEnd;
+            }
+            return map.get(word.charAt(0)).search(word.substring(1));
+        }
+        return false;
+    }
+
+    public boolean startsWith(String prefix) {
+        if (map.containsKey(prefix.charAt(0))) {
+            if (prefix.length() == 1) {
+                return true;
+            }
+            return map.get(prefix.charAt(0)).startsWith(prefix.substring(1));
+        }
+        return false;
+    }
+}
+
+/**
+ * Your Trie object will be instantiated and called as such:
+ * Trie obj = new Trie();
+ * obj.insert(word);
+ * boolean param_2 = obj.search(word);
+ * boolean param_3 = obj.startsWith(prefix);
+ */