added ternary trie implementation

tries/include/ternarytrie.h

@@ -0,0 +1,72 @@
+#ifndef AD3_TERNARYTRIE
+#define AD3_TERNARYTRIE
+
+/**
+ * The implementation of a Ternary Trie.
+ *
+ * Each node should be represented by a binary tree in order to reduce the memory usage.
+ */
+
+#include <stdbool.h>
+#include <stddef.h>
+
+/**
+ * Type definition for the struct representing the current Trie.
+ *
+ * You can (and should) redefine this in your c-file with the concrete fields.
+ */
+typedef struct ttrie TernaryTrie;
+
+/**
+ * Allocate and initialize an empty Trie.
+ *
+ * @return a pointer to an empty Trie struct
+ */
+TernaryTrie* ternarytrie_init();
+
+/**
+ * De-allocate a trie by freeing the memory occupied by this trie.
+ *
+ * @param trie which should be freed
+ */
+void ternarytrie_free(TernaryTrie* trie);
+
+/**
+ * Search whether a string is contained in this trie.
+ *
+ * @param trie
+ * @param string
+ * @return true if the string is contained within this trie, false otherwise
+ */
+bool ternarytrie_search(TernaryTrie* trie, const char* string);
+
+/**
+ * Add a string to this trie.
+ *
+ * @param trie
+ * @param string
+ * @return true if the trie was changed by this operation, false if it was already present
+ */
+bool ternarytrie_add(TernaryTrie* trie, const char* string);
+
+/**
+ * Remove a string from this trie.
+ *
+ * Note: strings added to this trie are considered to be "owned" by the caller.
+ * Removing the string from the trie should not free the string's memory.
+ *
+ * @param trie
+ * @param string
+ * @return true if the string was present and has been removed, false if it was not present
+ */
+bool ternarytrie_remove(TernaryTrie* trie, const char* string);
+
+/**
+ * Returns the number of strings in this trie.
+ *
+ * @param trie
+ * @return the number of strings in this trie
+ */
+size_t ternarytrie_size(TernaryTrie* trie);
+
+#endif //AD3_TERNARYTRIE