学步园

题目链接：hdu 2072 单词数

题目大意：略。

解题思路：建字典树，有多少个单词节点即有多少个不同的单词。

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int maxn = 1000005;
const int sigma_size = 26;

struct Tire {
    int sz;
    int g[maxn][sigma_size];
    int val[maxn];

    void init();
    int idx(char ch);
    void insert(char* s);
    int find(char* s);
}S;

int ans;
char op[maxn], w[105];

void solve () {
    ans = 0;
    S.init();

    int len = strlen(op), p = 0;
    for (int i = 0; i <= len; i++) {
        if (op[i] >= 'a' && op[i] <= 'z')
            w[p++] = op[i];
        else {
            if (p == 0)
                continue;

            w[p] = '\0';
            S.insert(w);
            p = 0;
        }
    }
    printf("%d\n", ans);
}

int main () {

    while (gets(op) && strcmp(op, "#"))
        solve();
    return 0;
}

void Tire::init() {
    sz = 1;
    val[0] = 0;
    memset(g[0], 0, sizeof(g[0]));
}

int Tire::idx (char ch) {
    return ch - 'a';
}

int Tire::find(char* s) {
    int u = 0, n = strlen(s);

    for (int i = 0; i < n; i++) {
        int v = idx(s[i]);

        if (g[u][v] == 0)
            return 0;
        u = g[u][v];
    }
    return val[u];
}

void Tire::insert(char* s) {
    int u = 0, n = strlen(s);

    for (int i = 0; i < n; i++) {
        int v = idx(s[i]);

        if (g[u][v] == 0) {
            val[sz] = 0;
            memset(g[sz], 0, sizeof(g[sz]));
            g[u][v] = sz++;
        }

        u = g[u][v];
    }
    if (val[u] == 0)
        ans++;
    val[u] = 1;
}