HDU1251字典树

这题还是一样的题型，插入和查询，这次查询find函数中要注意的就是如果遍历到一个结点之后对应的next指针为空，就返回0。

用cnt记录前缀出现次数，这时候就不用danger标记了。

 

我的代码：

#include <vector>#include <list>#include <map>#include <set>#include <deque>#include <queue>#include <algorithm>#include <stack>#include <bitset>#include <functional>#include <numeric>#include <utility>#include <sstream>#include <iostream>#include <iomanip>#include <cstdlib>#include <cstdio>#include <cstring>#include <cctype>#include <string>#include <ctime>#include <cmath>using namespace std;const int MAX=1000000;struct Node{int cnt;Node* ne[26];}node[MAX],*root;int K;Node* New(){Node* ret=&node[K++];ret->cnt=0;for(int i=0;i<26;i++){ret->ne[i]=NULL;}return ret;}void init(){K=0;root=New();}void insert(char* s){char* p=s;Node* ptr=root;int id;while(*p){id=*(p++)-'a';ptr->cnt++;if(ptr->ne[id]==NULL){ptr->ne[id]=New();}ptr=ptr->ne[id];}ptr->cnt++;}int find(char* s){char* p=s;Node* ptr=root;int id;while(*p){id=*(p++)-'a';if(ptr->ne[id]==NULL){return 0;}ptr=ptr->ne[id];}return ptr->cnt;}int main(){char s[120];init();while(gets(s),*s){insert(s);}while(gets(s)){printf("%d/n",find(s));}return 0;}