Merge pull request #41 from shashikedissanayake/master

Trie Data structure implimentation

data_structures/Trie/Trie.c

@@ -0,0 +1,184 @@
+/*------------------Trie Data Structure----------------------------------*/
+/*-------------Implimented for search a word in dictionary---------------*/
+
+/*-----character - 97 used for get the character from the ASCII value-----*/
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define ALPHABET_SIZE 26
+
+/*--Node in the Trie--*/
+typedef struct TrieNode
+{
+    struct TrieNode *children[ALPHABET_SIZE];
+    char character;
+    bool isEndOfWord;
+    
+} TrieNode;
+
+/*--Create new node--*/
+TrieNode *createTrieNode() 
+{	
+	TrieNode *node;
+    node = malloc(sizeof(TrieNode));
+	node->isEndOfWord = false;
+    int i = 0;
+    while(i<ALPHABET_SIZE){
+        node->children[i] = NULL;
+        i++;
+    }
+    return node; 
+}
+
+/*--Insert new word to Trie--*/
+void insert(TrieNode *root,char *word) 
+{
+	/*----Addition of the word done by recurcively----*/
+	
+	//Check wheather word character pointer is NULL  
+	if((strlen(word)-1) != 0)	
+	{
+		char character = *word;
+		if(root->children[character-97] == NULL)
+		{
+			TrieNode *node = NULL;
+			node = createTrieNode();
+			node->character = character;
+			root->children[character-97] = node;
+		}
+            word++;
+            insert(root->children[character-97],word);
+	}
+	else
+	{
+		root->isEndOfWord = true;
+	}
+	return;
+}
+
+/*--Search a word in the Trie--*/
+TrieNode *search( TrieNode *root, char *word)
+{
+	TrieNode *temp;
+	while(*word != '\0')
+	{
+		char character = *word;
+		if(root->children[character - 97] != NULL)
+		{
+			temp = root->children[character-97];
+			word++;
+			root = temp;
+		}
+		else
+		{
+			printf("No possible words!!\n");
+			return NULL;
+		}
+	}
+	return root;
+}
+
+/*---Print a word in the array--*/
+void printArray(char chars[], int len) 
+{
+	  int i;
+	  for (i=0; i<len; i++) 
+	  {
+		printf("%c", chars[i]);
+	  }
+	  printf("\n");
+}
+
+/*---Return all the related words------*/
+void printPathsRecur(TrieNode* node, char prefix[], int filledLen) 
+{
+	  if (node==NULL) return;
+
+	  prefix[filledLen] = node->character;
+	  filledLen++;
+
+	  if (node->isEndOfWord) 
+	  {
+		printArray(prefix, filledLen);
+	  }
+
+	  int i ;
+	  for(i=0;i<ALPHABET_SIZE;i++)
+	  {
+		printPathsRecur(node->children[i], prefix, filledLen);
+	  }
+}
+
+/*--Travel through the Trie and return words from it--*/
+void traverse(char prefix[], TrieNode *root) 
+{
+    TrieNode *temp = NULL;
+    temp = search(root,prefix);
+    int j=0;
+    while(prefix[j]!='\0')
+    {
+        j++;
+    }
+	printPathsRecur(temp,prefix,j-1);
+}
+
+/*------Demonstrate purposes uses text file called dictionary -------*/
+
+#define NUMBER_OF_WORDS (354935)
+#define INPUT_WORD_SIZE (100)
+
+/*----Get input from the user------*/
+char *receiveInput(char *s)
+{
+    scanf("%99s", s);
+    return s;
+}
+
+int main() 
+{
+	//Read the file dictionary
+    int word_count = 0;
+    char* words[NUMBER_OF_WORDS];
+    FILE *fp = fopen("dictionary.txt", "r");
+    
+    if (fp == 0)
+    {
+        fprintf(stderr, "Error while opening dictionary file");
+        exit(1);
+    }
+    
+    words[word_count] = malloc(INPUT_WORD_SIZE);
+    
+    while (fgets(words[word_count], INPUT_WORD_SIZE, fp)) 
+    {
+        word_count++;
+        words[word_count] = malloc(INPUT_WORD_SIZE);
+    }
+
+
+    //Push the words in to Trie 
+    TrieNode *root = NULL;
+    root = createTrieNode();
+    int i;
+    for(i=0;i<NUMBER_OF_WORDS;i++)
+    {
+      insert(root,words[i]);
+    }
+
+    while (1) 
+    {
+        printf("Enter keyword: ");
+        char str[100];
+        receiveInput(str);
+        printf("\n==========================================================\n");
+        printf("\n********************* Possible Words ********************\n");
+ 
+       //Find the word through the Trie
+        traverse(str,root);
+
+        printf("\n==========================================================\n");
+    }
+}