字典樹實現map容器

通過hdoj1075來演示如何通過字典樹創建map容器

字典樹的結構如下

其中，根結點上不存儲數據，每個結點有唯一的字符串(key)標示，可在對應的結點中存儲相應的值(value),比如ah結點上可以存儲數據"I am handsome!"

那麼，對應的map中一條爲["ah" -> "I am handsome!"],字典樹的數據結構中最多有MAX個子樹，假如由26個英文字母組成的字典樹，那麼MAX就是26

#include <iostream>
#include <string>
#define MAX 26
using namespace std;
//字典樹的數據結構
struct Trie {
  Trie *next[MAX];
  string v;
  Trie():v("") {
    for (int i = 0; i < MAX; ++i) {
      next[i] = NULL;
    }
  }
};

Trie *root = new Trie();
//插入一條數據
void createTrie(const string& value,const string& key) {
    int len = key.size();
    Trie *p = root;
    for(int i = 0; i < len; ++i) {
        int id = key[i] - 'a';
        if (p->next[id] == NULL) {
          p->next[id] = new Trie();
        }
        p = p->next[id];
    }
    p->v = value;
}
//查找數據
const string& find(const string& key) {
    int len = key.size();
    Trie *p = root;
    for(int i = 0; i < len; ++i) {
        int id = key[i] - 'a';
        if (p->next[id] == NULL)  return key;
        p = p->next[id];
    }
    if (p->v == "") return key;
    else return p->v;
}

int main() {
 // freopen("1.in", "r", stdin);
  //建立字典樹
  string key, value, s, tmp;
  cin >> value;
  while (cin >> value && value != "END") {
    cin >> key;
    createTrie(value, key);
  }
  getchar();
  getline(cin, tmp);
  while (getline(cin, tmp) && tmp != "END") {
    s += tmp + "\n";
  }
  tmp = "";
  for (int i = 0; i < s.length(); ++i) {
    if (s[i] > 'z' || s[i] < 'a')
      cout << s[i];
    else
      tmp += s[i];
    if (i == s.length() || (s[i+1] > 'z' || s[i+1] < 'a')) {
      cout << find(tmp);
      tmp = "";
    }
  }
  return 0;
}