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trie_search_word.cpp
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trie_search_word.cpp
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// C++ implementation of search and insert
// operations on Trie
#include <bits/stdc++.h>
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 NULLs)
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;
}
// Returns true if key presents in trie, else
// false
bool search(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])
return false;
pCrawl = pCrawl->children[index];
}
return (pCrawl->isEndOfWord);
}
// Driver
int main()
{
// Input keys (use only 'a' through 'z'
// and lower case)
string keys[] = {"the", "a", "there",
"answer", "any", "by",
"bye", "their" };
int n = sizeof(keys)/sizeof(keys[0]);
struct TrieNode *root = getNode();
// Construct trie
for (int i = 0; i < n; i++)
insert(root, keys[i]);
// Search for different keys
search(root, "the")? cout << "Yes\n" :
cout << "No\n";
search(root, "these")? cout << "Yes\n" :
cout << "No\n";
return 0;
}