HDU 1251 统计难题（字典树）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1251

题目思路：字典树模板题，上板子就行

代码：

#include<cstdio>
#include<cmath>
#include<cstring>
#include<string>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<queue>
#include<stack>
#include<map>

using namespace std;

#define FOU(i,x,y) for(int i=x;i<=y;i++)
#define FOD(i,x,y) for(int i=x;i>=y;i--)
#define MEM(a,val) memset(a,val,sizeof(a))
#define PI acos(-1.0)

const double EXP = 1e-9;
typedef long long ll;
typedef unsigned long long ull;
const int INF = 0x3f3f3f3f;
const ll MINF = 0x3f3f3f3f3f3f3f3f;
const double DINF = 0xffffffffffff;
const int mod = 1e9+7;
const int N = 1e6+5;

const int MAXN = 1000005;  //数组第一维大小，字符串的个数*最大长度
struct DicTree{
    int cnt[MAXN];  //代表某个前缀的单词总个数
    int tree[MAXN][26];
    int tot;

    /*void init(){
        //特别说明多组数据才用init,否则一般不用,因为这种多个字符串输入一般都是一组数据
        MEM(cnt,0);
        MEM(tree,0);
        tot=0;
    }*/

    void Insert(char *s){
        int len = strlen(s);
        int now=0;
        for(int i=0;i<len;i++){
            int id = s[i]-'a';
            if(!tree[now][id]){
                tree[now][id] = ++tot;
            }
            now = tree[now][id];
            cnt[now]++;
        }
    }

    int Search(char *s){
        int len=strlen(s);
        int now=0;
        for(int i=0;i<len;i++){
            int id = s[i]-'a';
            if(!tree[now][id])
                return 0;
            now=tree[now][id];
        }
        return cnt[now];
    }
}dictree;


int main()
{
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    std::ios::sync_with_stdio(false);
    char s[20];
    while(gets(s)){
        if(s[0]=='\0')
            break;
        dictree.Insert(s);
    }

    while(gets(s))
    {
        printf("%d\n",dictree.Search(s));
    }
    return 0;
}