UVA 1401 Remember the Word (trie + dp)

第一次写trie, 看别人的代码看懂的，顺便学了一下dp。

#include <iostream>
#include <cstring>
#include <cstdio>
#include <vector>
#define mod 20071027;
using namespace std;

char str[300010], s[110];
int dp[300010];
struct Trie
{
int ch[400010][26];
int val[400010];
int sz;
void clearr()
{
sz = 1;
memset(ch, 0, sizeof(ch));
}
int idc(char c)
{
return c - 'a';
}
void insertt(char *s, int lenn)
{
int u = 0;
for(int i = 0; i < lenn; i++)
{
int c = idc(s[i]);
if(!ch[u][c])
{
val[sz] = 0;
ch[u][c] = sz++;
}
u = ch[u][c];
}
val[u] = lenn;
}
void find_prefix(char *s, int len, vector<int>& ans)
{
int u = 0;
for(int i = 0; i < len; i++)
{
int c = idc(s[i]);
if(ch[u][c])
{
u = ch[u][c];
if(val[u])
ans.push_back(val[u]);
}
else
break;
}
}
}test;

int main()
{
int kase = 0;
while(~scanf("%s", str))
{
memset(dp, 0, sizeof(dp));
int len = strlen(str);
test.clearr();
int S;
scanf("%d", &S);
for(int i = 1; i <= S; i++)
{
scanf("%s", s);
int lenn = strlen(s);
test.insertt(s, lenn);
}

dp[len] = 1;
for(int i = len - 1; i >= 0; i--)
{
vector<int> ans;
test.find_prefix(str + i, len - i, ans);
for(int j = 0; j < ans.size(); j++)
{
dp[i] = (dp[i] + dp[i + ans[j]]) % mod;
}
}
printf("Case %d: %d\n", ++kase, dp[0]);
}
}