Check if the given Trie contains words starting from every alphabet

Given a Trie, the task is to check if it contains words starting from every alphabet from [a – z].

Examples:

Input: keys[] = {“element”, “fog”, “great”, “hi”,
“ok”, “ios”, “parrot”, “quiz”, “kim”, “mango”, “nature”, “apple”,
“ball”, “cat”, “dog”, “lime”, “ruby”, “shine”, “tinkter”,
“ultra”, “volly”, “wow”, “xerox”, “yak”, “zenon”, “joke”}
Output: Yes

Input: keys[] = {“geeks”, “for”, “geeks”}
Output: No

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: We just need to focus on the root node of the given Trie and no need to traverse other nodes. We simply check if Trie has all its child pointers pointing to valid nodes i.e. there are words starting from every character of the alphabet.

Below is the implementation of the above approach:

 `// C++ implementation of the approach ` `#include ` `using` `namespace` `std; ` ` `  `const` `int` `ALPHABET_SIZE = 26; ` ` `  `// Trie node ` `struct` `TrieNode { ` `    ``struct` `TrieNode* children[ALPHABET_SIZE]; ` ` `  `    ``// isEndOfWord is true if the node represents ` `    ``// end of a word ` `    ``bool` `isEndOfWord; ` `}; ` ` `  `// Returns new trie node (initialized to NULL) ` `struct` `TrieNode* getNode(``void``) ` `{ ` `    ``struct` `TrieNode* pNode = ``new` `TrieNode; ` ` `  `    ``pNode->isEndOfWord = ``false``; ` ` `  `    ``for` `(``int` `i = 0; i < ALPHABET_SIZE; i++) ` `        ``pNode->children[i] = NULL; ` ` `  `    ``return` `pNode; ` `} ` ` `  `// If not present, inserts key into trie ` `// If the key is prefix of trie node, just ` `// marks leaf node ` `void` `insert(``struct` `TrieNode* root, string key) ` `{ ` `    ``struct` `TrieNode* pCrawl = root; ` ` `  `    ``for` `(``int` `i = 0; i < key.length(); i++) { ` `        ``int` `index = key[i] - ``'a'``; ` `        ``if` `(!pCrawl->children[index]) ` `            ``pCrawl->children[index] = getNode(); ` ` `  `        ``pCrawl = pCrawl->children[index]; ` `    ``} ` ` `  `    ``// Mark last node as leaf ` `    ``pCrawl->isEndOfWord = ``true``; ` `} ` ` `  `// Function to check if Trie contains words ` `// starting from all the alphabets ` `bool` `containsAll(TrieNode* root) ` `{ ` `    ``// We check if root node has all childs ` `    ``// if None of them is NULL then we return true ` `    ``for` `(``int` `i = 0; i < 26; i++) { ` ` `  `        ``// If there is no word in the trie starting ` `        ``// from the current alphabet ` `        ``if` `(root->children[i] == NULL) ` `            ``return` `false``; ` `    ``} ` `    ``return` `true``; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` ` `  `    ``string keys[] = { ``"element"``, ``"fog"``, ``"great"``, ``"hi"``, ``"ok"``, ` `                      ``"ios"``, ``"parrot"``, ``"quiz"``, ``"kim"``, ``"mango"``, ``"nature"``, ` `                      ``"apple"``, ``"ball"``, ``"cat"``, ``"dog"``, ``"lime"``, ``"ruby"``, ` `                      ``"shine"``, ``"tinkter"``, ``"ultra"``, ``"volly"``, ``"wow"``, ` `                      ``"xerox"``, ``"yak"``, ``"zenon"``, ``"joke"` `}; ` `    ``int` `n = ``sizeof``(keys) / ``sizeof``(keys[0]); ` ` `  `    ``// Create the Trie ` `    ``struct` `TrieNode* root = getNode(); ` `    ``for` `(``int` `i = 0; i < n; i++) ` `        ``insert(root, keys[i]); ` ` `  `    ``// If trie contains words starting ` `    ``// from every alphabet ` `    ``if` `(containsAll(root)) ` `        ``cout << ``"Yes"``; ` `    ``else` `        ``cout << ``"No"``; ` ` `  `    ``return` `0; ` `} `

Output:

```Yes
```

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