W4:Q3: StreamofCharacters

README.md

@@ -62,6 +62,8 @@ Q. [The Maze](https://leetcode.com/explore/challenge/card/august-leetcoding-chal
 
 Q. [Random Point in Non-overlapping Rectangles](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/552/week-4-august-22nd-august-28th/3433/)  ➡️ [Solution](https://github.com/abhisheksurve45/leetcode-aug-2020/blob/master/WEEK3/RandomPointinNonoverlappingRectangles.java)
 
+Q. [Stream of Characters](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/552/week-4-august-22nd-august-28th/3434/)  ➡️ [Solution](https://github.com/abhisheksurve45/leetcode-aug-2020/blob/master/WEEK3/StreamofCharacters.java)
+
 ## WEEK 5 🚧
 
 [Coming soon](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/)

WEEK4/StreamofCharacters.java

@@ -0,0 +1,53 @@
+public class StreamofCharacters {
+
+    class StreamChecker {
+
+        private class TrieNode {
+            private TrieNode[] next = new TrieNode[26];
+            private boolean isWord;
+        }
+
+        private TrieNode root;
+        private StringBuilder sb;
+
+        public StreamChecker(String[] words) {
+
+            this.root = new TrieNode();
+            this.sb = new StringBuilder();
+
+            for (String str : words) {
+                int len = str.length();
+                TrieNode node = root;
+
+                for (int i = len - 1; i >= 0; i--) {
+                    char c = str.charAt(i);
+                    if (node.next[c - 'a'] == null) node.next[c - 'a'] = new TrieNode();
+                    node = node.next[c - 'a'];
+                }
+
+                node.isWord = true;
+            }
+        }
+
+        public boolean query(char letter) {
+
+            sb.append(letter);
+            TrieNode node = root;
+
+            for (int i = sb.length() - 1; i >= 0 && node != null; i--) {
+                node = node.next[sb.charAt(i) - 'a'];
+                if (node != null && node.isWord) {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+    }
+
+    /**
+     * Your StreamChecker object will be instantiated and called as such:
+     * StreamChecker obj = new StreamChecker(words);
+     * boolean param_1 = obj.query(letter);
+     */
+}