TheAlgorithms-C-Plus-Plus/data_structure/trie_tree.cpp

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <iostream>

// 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();
    char hello[] = "hello";
    char world[] = "world";
    char word[] = "word";
    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;
}