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  1. // C++ implementation of search and insert
  2. // operations on Trie
  3. #include <bits/stdc++.h>
  4. using namespace std;
  5.  
  6. const int ALPHABET_SIZE = 26;
  7.  
  8. // trie node
  9. struct TrieNode
  10. {
  11. 	struct TrieNode *children[ALPHABET_SIZE];
  12.  
  13. 	// isEndOfWord is true if the node represents
  14. 	// end of a word
  15. 	bool isEndOfWord;
  16. };
  17.  
  18. // Returns new trie node (initialized to NULLs)
  19. struct TrieNode *getNode(void)
  20. {
  21. 	struct TrieNode *pNode = new TrieNode;
  22.  
  23. 	pNode->isEndOfWord = false;
  24.  
  25. 	for (int i = 0; i < ALPHABET_SIZE; i++)
  26. 		pNode->children[i] = NULL;
  27.  
  28. 	return pNode;
  29. }
  30.  
  31. // If not present, inserts key into trie
  32. // If the key is prefix of trie node, just
  33. // marks leaf node
  34. void insert(struct TrieNode *root, string key)
  35. {
  36. 	struct TrieNode *pCrawl = root;
  37.  
  38. 	for (int i = 0; i < key.length(); i++)
  39. 	{
  40. 		int index = key[i] - 'a';
  41. 		if (!pCrawl->children[index])
  42. 			pCrawl->children[index] = getNode();
  43.  
  44. 		pCrawl = pCrawl->children[index];
  45. 	}
  46.  
  47. 	// mark last node as leaf
  48. 	pCrawl->isEndOfWord = true;
  49. }
  50.  
  51. // Returns true if key presents in trie, else
  52. // false
  53. bool search(struct TrieNode *root, string key)
  54. {
  55. 	struct TrieNode *pCrawl = root;
  56.  
  57. 	for (int i = 0; i < key.length(); i++)
  58. 	{
  59. 		int index = key[i] - 'a';
  60. 		if (!pCrawl->children[index])
  61. 			return false;
  62.  
  63. 		pCrawl = pCrawl->children[index];
  64. 	}
  65.  
  66. 	return (pCrawl != NULL && pCrawl->isEndOfWord);
  67. }
  68.  
  69. // Driver
  70. int main()
  71. {
  72. 	// Input keys (use only 'a' through 'z'
  73. 	// and lower case)
  74. 	string keys[] = {"the", "a", "there",
  75. 					"answer", "any", "by",
  76. 					"bye", "their" };
  77. 	int n = sizeof(keys)/sizeof(keys[0]);
  78.  
  79. 	struct TrieNode *root = getNode();
  80.  
  81. 	// Construct trie
  82. 	for (int i = 0; i < n; i++)
  83. 		insert(root, keys[i]);
  84.  
  85. 	// Search for different keys
  86. 	search(root, "the")? cout << "Yes\n" :
  87. 						cout << "No\n";
  88. 	search(root, "these")? cout << "Yes\n" :
  89. 						cout << "No\n";
  90. 	return 0;
  91. }
  92.  
Success #stdin #stdout 0.01s 5576KB
comments (?)
stdin
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Standard input is empty
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Yes
No
https://ideone.com/rbdik5
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
public

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