C ++程序实现Trie
在这里，我们将讨论用于实现Trie的C++程序。它是基于树的数据结构，用于有效地检索大型字符串数据集中的键。
函数和伪代码
Begin
function insert() :
If key not present, inserts key into trie. If the key is prefix of trie node, just mark leaf node.
End
Begin
function deleteNode() If tree is empty then return null.
If last character of the key is being processed,
then that node will be no more end of string after deleting it.
If given key is not prefix of any other string, then delete it and set root = NULL.
If key is not the last character,
Then recur for the child which will be obtained by using ASCII value.
If root does not have any child left and it is not end of another word,
Then delete it and set root = NULL.
End示例
#include <bits/stdc++.h>
using namespace std;
const int ALPHA_SIZE = 26;
struct Trie {
struct Trie *child[ALPHA_SIZE];
bool endofstring; //It is true if node represents end of word.
};
struct Trie *createNode(void) //creation of new node {
struct Trie *tNode = new Trie;
tNode->endofstring = false;
for (int i = 0; i < ALPHA_SIZE; i++)
tNode->child[i] = NULL;
return tNode;
}
void insert(struct Trie *root, string key) {
struct Trie *curr = root;
for (int i = 0; i < key.length(); i++) {
int index = key[i] - 'A';
if (!curr->child[index])
curr->child[index] = createNode();
curr = curr->child[index];
}
curr->endofstring= true; //last node as leaf
}
bool search(struct Trie *root, string key) { //check if key is present in trie. If present returns true
struct Trie *curr = root;
for (int i = 0; i < key.length(); i++) {
int index = key[i] - 'A';
if (!curr->child[index])
return false;
curr = curr->child[index];
}
return (curr != NULL && curr->endofstring);
}
bool isEmpty(Trie* root) //check if root has children or not {
for (int i = 0; i < ALPHA_SIZE; i++)
if (root->child[i])
return false;
return true;
}
Trie* deletion(Trie* root, string key, int depth = 0) {
//如果树为空，则返回null。
if (!root)
return NULL;
if (depth == key.size()) { //If last character of key is being processed,
if (root->endofstring)
root->endofstring = false; //then that node will be no more end of string after deleting it.
if (isEmpty(root)) { //If given key is not prefix of any other string,
delete (root);
root = NULL;
}
return root;
}
//如果键不是最后一个字符，
int index = key[depth] - 'A';
root->child[index] =
deletion(root->child[index], key, depth + 1); //Then recur for the child which will be obtained by using ASCII value.
if (isEmpty(root) && root->endofstring == false) { //If root does not have any child leftand it is not end of another word
delete (root);
root = NULL;
}
return root;
}
int main() {
string inputs[] = {"HELLOWORLD","HI","BYE", "THE","THENA"}; // Input keys ( only A to Z in upper case)
int n = sizeof(inputs)/sizeof(inputs[0]);
struct Trie *root = createNode();
for (int i = 0; i < n; i++)
insert(root, inputs[i]);
search(root, "HELLOWORLD")? cout << "Key is Found\n" :
cout << "Key is not Found\n";
search(root, "HE")? cout << "Key is Found\n" :
cout << "Key is not Found\n";
deletion(root, "THEN")? cout << "Key is deleted\n" :
cout << "Key is not Deleted\n";
return 0;
}输出结果
Key is Found Key is not Found Key is deleted