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Trie.cpp
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79 lines (62 loc) · 1.88 KB
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#include <bits/stdc++.h>
using namespace std;
const int SIZE = 26;
struct MyNode{
struct MyNode *children[SIZE];
bool isEndOfWord;
};
// Returns new trie node
struct MyNode *getNode(void)
{
struct MyNode *pNode = new MyNode;
pNode->isEndOfWord = false;
for (int i = 0; i < 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 MyNode *root, string key)
{
struct MyNode *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 MyNode *root, string key)
{
struct MyNode *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 != NULL && pCrawl->isEndOfWord);
}
// Driver Programme to check above functions
int main()
{
// For input keys use only lower case
string keys[] = {"the", "a", "there",
"answer", "any", "by",
"bye", "their" };
int n = sizeof(keys)/sizeof(keys[0]);
struct MyNode *root = getNode();
// Build trie
for (int i = 0; i < n; i++)
insert(root, keys[i]);
// Search for different keys to check is it present in our dictonary or not..??
search(root, "the")? cout << "Yes\n" : cout << "No\n";
search(root, "these")? cout << "Yes\n" : cout << "No\n";
return 0;
}