uvalive3942(前缀树)

题意：

给出一个字符串，然后给出ｎ个单词，问这个串分解成单词，有几种分法；

思路：

用Trie树；

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

using namespace std;
const int N = 300000 + 5;
const int MOD = 20071027;
char s[N];
int val[N], ch[N][30], sz, dp[N];

void Insert(char *str) {
    int u = 0, n = strlen(str);
    for (int i = 0; i < n; i++) {
        int c = str[i] - 'a';
        if (ch[u][c] == 0) {
            memset(ch[sz], 0, sizeof(ch[sz]));
            val[sz] = 0;
            ch[u][c] = sz++;
        }
        u = ch[u][c];
    }
    val[u] = 1;
}

int main() {
    int n, cas = 1;
    while (scanf("%s", s) == 1) {
        memset(dp, 0, sizeof(dp));
        sz = 1;
        memset(ch[0], 0, sizeof(ch[0]));
        scanf("%d", &n);
        char str[200];
        for(int i = 0; i < n; i++) {
            scanf("%s", str);
            Insert(str);
        }
        int len = strlen(s);
        int sum = 0;
        dp[len] = 1;
        for (int i = len - 1; i >= 0; i--) {
            int u = 0, l = len - i;
            for (int j = 0; j < l; ++j) {
                if (s[i + j] == 0) 
					break;
                int c = s[i + j] - 'a';
                if (ch[u][c] == 0)
                    break;
                u = ch[u][c];
                if (val[u])
                    dp[i] = (dp[i] + dp[i + j + 1]) % MOD;
            }
        }
        printf("Case %d: %d\n",cas++ ,dp[0]);
    }
    return 0;
}