Timus 1545. Hieroglyphs Trie的即学即用 实现字典提示功能

前面学了Trie，那么就即学即用，运用Trie数据结构来解决这道题目。

本题目比较简单，当然可以不使用Trie，不过多用高级数据结构还是很有好处的。

题目：

Vova is fond of anime. He is so enthusiastic about this art that he learned to communicate with his Japanese friends using their native language. However, for writing email messages Vova has to use Latin letters. He wants to type hieroglyphs from his keyboard. His team-mate Sergey, in order to help Vova, created an applet that makes it possible to write hieroglyphs by means of typing Latin letters on the keyboard. Each hieroglyph is represented by a sequence of two Latin letters. This correspondence is given in a special reference book compiled by Sergey. When the applet realizes that a sequence of Latin letters corresponding to a hieroglyph has been typed, it replaces the sequence with this hieroglyph.

When Vova started using Sergey's program, he quickly became bored of looking into the reference book so often. Help Sergey to upgrade the applet in such a way that for each typed Latin letter it would automatically supply a prompt helping to continue this letter to a sequence representing a hieroglyph.

Input

The first line contains the number of hieroglyphs in Sergey's reference bookN(1≤N≤1000). Each of the nextNlines contains a sequence of two lowercase Latin letters corresponding to a hieroglyph. The next line contains a lowercase Latin letter entered by Vova.

Output

Output sequences from the reference book that start with the given letter, one sequence per line, in an arbitrary order. If there are no such sequences, then output nothing.

Sample

input	output
6 na no ni ki ka ku k	ka ki ku

本题就是实现一个简单的字典提示功能，可以使用hash表的方法来做，实现起来也很简单。

这里我做了个Trie Class来实现:

#include <iostream>
using namespace std;

#define ALPHA_SIZE 26
#define CHAR_TO_INDEX(c) (c - 'a')

struct HieroglyphsTrie_Node
{
	int val;
	HieroglyphsTrie_Node *children[ALPHA_SIZE];
};

struct HieroglyphsTrie
{
	HieroglyphsTrie_Node *root;
	int size;
};

class HieroglyphsTrieClass
{
	HieroglyphsTrie *pTrie;
public:
	HieroglyphsTrieClass()
	{
		pTrie = (HieroglyphsTrie *) malloc (sizeof(HieroglyphsTrie));
		init();
	}

	HieroglyphsTrie_Node *getNode()
	{
		HieroglyphsTrie_Node *pNode = nullptr;
		pNode = (HieroglyphsTrie_Node *)malloc(sizeof(HieroglyphsTrie_Node));
		if (pNode)
		{
			pNode->val = 0;
			for (int i = 0; i < ALPHA_SIZE; i++)
			{
				pNode->children[i] = nullptr;
			}
		}
		return pNode;
	}

	void init()
	{
		pTrie->root = getNode();
		pTrie->size = 0;
	}

	void insert(const char key[])
	{
		int len = strlen(key);
		int id = 0;
		HieroglyphsTrie_Node *pCrawl = pTrie->root;
		pTrie->size++;
		for (int lv = 0; lv < len; lv++)
		{
			id = CHAR_TO_INDEX(key[lv]);
			if (!pCrawl->children[id])
			{
				pCrawl->children[id] = getNode();
			}
			pCrawl = pCrawl->children[id];
		}
		pCrawl->val = pTrie->size;
	}

	int search(char key[])
	{
		int len = strlen(key);
		int id = 0;
		HieroglyphsTrie_Node *pCrawl = pTrie->root;
		for (int lv = 0; lv < len; lv++)
		{
			id = CHAR_TO_INDEX(key[lv]);
			if (!pCrawl->children[id]) return 0;
			pCrawl = pCrawl->children[id];
		}
		return (int)(0 != pCrawl->val);
	}

	void HieroglyphsRun()
	{
		int n = 0;
		cin>>n;
		char ch[3];//不能是ch[2]，因为后面还要多一个'\0'终止符
		while (n--)
		{
			cin>>ch;
			insert(ch);
		}
		char k;
		cin>>k;

		HieroglyphsTrie_Node *pCrawl = nullptr;
		pCrawl = pTrie->root->children[CHAR_TO_INDEX(k)];
		if (pCrawl)
		{
			for (int i = 0; i < ALPHA_SIZE; i++)
			{
				if (pCrawl->children[i])
				{
					cout<<k<<char('a'+i)<<endl;
				}
			}
		}
	}
};

int main()
{
	HieroglyphsTrieClass hie;
	hie.HieroglyphsRun();
	return 0;
}

本类暂时还是不是完善的，慢慢完善吧，不过可以很好完成本题了。