🎉 Day 23

Author: AkashRajpurohit

README.md

@@ -37,6 +37,7 @@
 ## Week 4 🚧
 
 1. [Random Point in Non-overlapping Rectangles](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/552/week-4-august-22nd-august-28th/3433/) ➡️ [CPP Solution](Week4/randomPoint.cpp)
+2. [Stream of Characters](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/552/week-4-august-22nd-august-28th/3434/) ➡️ [CPP Solution](Week4/streamChecker.cpp)
 
 ## Week 5 🚧
 

Week4/streamChecker.cpp

@@ -0,0 +1,69 @@
+class StreamChecker {
+private:
+    class Trie {
+    public:
+        bool is_leaf;
+        Trie* children[26];
+        
+        Trie() {
+            this->is_leaf = false;
+            for(int i = 0; i < 26; ++i) {
+                this->children[i] = NULL;
+            }
+        }
+        
+        void insert_reversed(string word) {
+            reverse(word.begin(), word.end());
+            Trie* root = this;
+            
+            for(char c: word) {
+                int idx = c - 'a';
+                
+                if(root->children[idx] == NULL)
+                    root->children[idx] = new Trie();
+                
+                root = root->children[idx];
+            }
+            
+            root->is_leaf = true;
+        }
+            
+    };
+public:
+    Trie trie;
+    vector<char> queries;
+    int longest_word = 0;
+    
+    StreamChecker(vector<string>& words) {
+        for(auto& word: words) {
+            trie.insert_reversed(word);
+            
+            if(word.size() > longest_word)
+                longest_word = word.size();
+        }
+    }
+    
+    bool query(char letter) {
+        queries.insert(queries.begin(), letter);
+        
+        if(queries.size() > longest_word)
+            queries.pop_back();
+        
+        Trie* curr = &trie;
+        
+        for(char c: queries) {
+            if(curr->is_leaf) return true;
+            if(curr->children[c - 'a'] == NULL) return false;
+            
+            curr = curr->children[c - 'a'];
+        }
+        
+        return curr->is_leaf;
+    }
+};
+
+/**
+ * Your StreamChecker object will be instantiated and called as such:
+ * StreamChecker* obj = new StreamChecker(words);
+ * bool param_1 = obj->query(letter);
+ */