Added Trie.cpp

CONTRIBUTORS.md

@@ -1,3 +1,4 @@
 # Add yourself in this file if you are a contributor for Hacktoberfest 2018
 
 - Radu Stochitoiu
+- Alin Georgescu

CPP/data-structures/Trie.cpp

@@ -0,0 +1,212 @@
+#include <vector>
+#include <string>
+#include <iostream>
+
+#define ALPHABET_SIZE  26
+
+using std::vector;
+using std::string;
+using std::cout;
+using std::endl;
+
+template <typename T>
+class Trie {
+ private:
+    int count, suffix;
+    vector<Trie<T> *> children;
+    T value;
+    bool isEndOfWord;
+  public:
+    Trie() {}
+
+    Trie(int capacity, T value)
+      : count(0),
+        suffix(0),
+        children(capacity, NULL),
+        value(value) { }
+
+    Trie(int capacity)
+      : count(0),
+        suffix(0),
+        children(capacity, NULL) { }
+
+    ~Trie() {}
+ 	void insert(string key, T value) {
+		if (!key.size()) {
+            this->value = value;
+            isEndOfWord = true;
+            return;
+        }
+
+        int x = 0;
+        if (!search(key, x))
+            ++suffix;
+
+        int nextNode = key[0] - 'a';
+        if (!children[nextNode]) {
+            children[nextNode] = new Trie<T>(ALPHABET_SIZE);
+            ++count;
+        }
+
+        key = key.erase(0, 1);
+        children[nextNode]->insert(key, value); 
+    }
+	bool search(string key, T &val) {
+        if (!key.size()) {
+            val = value;
+            return isEndOfWord;
+        }
+
+        int nextNode = key[0] - 'a';
+
+        if (!children[nextNode])
+            return false;
+
+        key = key.erase(0, 1);
+        return children[nextNode]->search(key, val);
+    }
+
+    bool hasChildren() {
+        for (int i = 0; i < ALPHABET_SIZE; ++i) {
+            if (children[i] != NULL)
+                return true;
+        }
+
+        return false;
+    }
+
+    bool remove(string key) {
+        if (!key.size()) {
+            isEndOfWord = false;
+            value = 0;
+            if (!hasChildren() && !isEndOfWord)
+                return true;
+        }
+
+        int nextNode = key[0] - 'a';
+
+        if (children[nextNode]) {
+            key = key.erase(0, 1);
+            --suffix;
+
+            if (children[nextNode]->remove(key)) {
+                delete children[nextNode];
+                --count;
+                if (!hasChildren() && !isEndOfWord)
+                    return true;
+            }
+        }
+
+        return false;
+    }
+
+    int numWordsWithPrefix(string prefix) {
+        if (!prefix.size()) {
+            return suffix;
+        }
+
+        int nextNode = prefix[0] - 'a';
+
+        if (!children[nextNode])
+            return 0;
+
+        prefix = prefix.erase(0, 1);
+        return children[nextNode]->numWordsWithPrefix(prefix);
+    }
+
+};
+
+int main() {
+    Trie<int> *trie = new Trie<int>(ALPHABET_SIZE);
+    string s;
+    int val;
+
+    s = "arta";
+    trie -> insert(s, 1);
+    s = "artilerie";
+    trie -> insert(s, 2);
+    s = "artist";
+    trie -> insert(s, 3);
+    s = "artistic";
+    trie -> insert(s, 4);
+    s = "arma";
+    trie -> insert(s, 5);
+    s = "pusca";
+    trie -> insert(s, 6);
+
+	if (!trie -> search(s, val)) {
+		cout << s << " should be in Trie\n";
+	}
+	cout << "Value of " << s << " : " << val << endl;
+	s = "artistic";
+	if (!trie -> search(s, val)) {
+		cout << s << " should be in Trie\n";
+	}
+	cout << "Value of " << s << " : " << val << endl;
+	s = "artist";
+	if (!trie -> search(s, val)) {
+		cout << s << " should be in Trie\n";
+	}
+	cout << "Value of " << s << " : " << val << endl;
+	s = "artilerie";
+	if (!trie -> search(s, val)) {
+		cout << s << " should be in Trie\n";
+	}
+	cout << "Value of " << s << " : " << val << endl;
+	s = "arma";
+	if (!trie -> search(s, val)) {
+		cout << s << " should be in Trie\n";
+	}
+	cout << "Value of " << s << " : " << val << endl;
+	s = "arta";
+	if (!trie -> search(s, val)) {
+		cout << s << " should be in Trie\n";
+	}
+	cout << "Value of " << s << " : " << val << endl;
+	s = "artis";
+	if (trie -> search(s, val)) {
+		cout << s << " should not be in Trie\n";
+	}
+	s = "pusca";
+	trie -> remove(s);
+	if (trie -> search(s, val)) {
+		cout << s << " should not be in Trie after removal\n";
+	}
+	s = "artilerie";
+	trie -> remove(s);
+	if (trie -> search(s, val)) {
+		cout << s << " should not be in Trie after removal\n";
+	}
+	s = "arta";
+	if (!trie -> search(s, val)) {
+		cout << s << " should still be in Trie\n";
+	}
+	s = "artist";
+	trie -> remove(s);
+	if (trie -> search(s, val)) {
+		cout << s << " should not be in Trie after removal\n";
+	}
+	s = "artistic";
+	if (!trie -> search(s, val)) {
+		cout << s << " should still be in Trie\n";
+	}
+
+	s = "artist";
+	trie -> insert(s, 3);
+	s = "artilerie";
+	trie -> insert(s, 3);
+	s = "pusca";
+	trie -> insert(s, 3);
+	s = "";
+	cout << trie->numWordsWithPrefix(s) << endl;
+	s = "a";
+	cout << trie->numWordsWithPrefix(s) << endl;
+	s = "art";
+	cout << trie->numWordsWithPrefix(s) << endl;
+	s = "arti";
+	cout << trie->numWordsWithPrefix(s) << endl;
+	s = "articulatie";
+	cout << trie->numWordsWithPrefix(s) << endl;
+
+    return 0;
+}