rename Data Structure -> data_structure (#644)

data_structure/TrieTree.cpp

@@ -0,0 +1,97 @@
+#include <iostream>
+#include <string.h>
+#include <stdbool.h>
+using namespace std;
+// structure definition
+typedef struct trie
+{
+    struct trie *arr[26];
+    bool isEndofWord;
+} trie;
+// create a new node for trie
+trie *createNode()
+{
+    trie *nn = new trie();
+    for (int i = 0; i < 26; i++)
+        nn->arr[i] = NULL;
+    nn->isEndofWord = false;
+    return nn;
+}
+
+// insert string into the trie
+void insert(trie *root, char *str)
+{
+    for (int i = 0; i < strlen(str); i++)
+    {
+        int j = str[i] - 'a';
+        if (root->arr[j])
+        {
+            root = root->arr[j];
+        }
+        else
+        {
+            root->arr[j] = createNode();
+            root = root->arr[j];
+        }
+    }
+    root->isEndofWord = true;
+}
+
+// search a string exists inside the trie
+bool search(trie *root, char *str, int index)
+{
+    if (index == strlen(str))
+    {
+        if (!root->isEndofWord)
+            return false;
+        return true;
+    }
+    int j = str[index] - 'a';
+    if (!root->arr[j])
+        return false;
+    return search(root->arr[j], str, index + 1);
+}
+/* removes the string if it is not a prefix of any  other 
+ string, if it is then just sets the endofword to false, else 
+ removes the given string*/
+bool deleteString(trie *root, char *str, int index)
+{
+    if (index == strlen(str))
+    {
+        if (!root->isEndofWord)
+            return false;
+        root->isEndofWord = false;
+        for (int i = 0; i < 26; i++)
+            return false;
+        return true;
+    }
+    int j = str[index] - 'a';
+    if (!root->arr[j])
+        return false;
+    bool var = deleteString(root, str, index + 1);
+    if (var)
+    {
+        root->arr[j] = NULL;
+        if (root->isEndofWord)
+            return false;
+        else
+        {
+            int i;
+            for (i = 0; i < 26; i++)
+                if (root->arr[i])
+                    return false;
+            return true;
+        }
+    }
+}
+
+int main()
+{
+    trie *root = createNode();
+    insert(root, "hello");
+    insert(root, "world");
+    int a = search(root, "hello", 0);
+    int b = search(root, "word", 0);
+    printf("%d %d ", a, b);
+    return 0;
+}