UVA 1401 Remember The Word (Trie + DP)

Test instructions: Give n (n<=4000) words and a string (len<=300000), to break the string into a number of words splicing, how many ways

Idea:Trie, first put the word into Trie, and then dp,dp[i] denotes the beginning of the first letter of the string, and then each state as long as the Trie tree found the corresponding letter beginning word, and then dp[i] = sum{dp[i + len (x)]} To make a state transition. This x is one of n words that can be queried with trie

Code

#include <cstdio> #include <cstring> #include <algorithm>using namespace std;const int maxn = 300005; const int MOD = 20071027;int ch[maxn][26];int val[maxn];int sz;int idx (char c) {return C ' a ';}    void Insert (char* s) {int u = 0;    int len = strlen (s);        for (int i = 0; i < len; i++) {int c = idx (s[i]);            if (!ch[u][c]) {memset (Ch[sz], 0, sizeof (Ch[sz]));            Val[sz] = 0;        CH[U][C] = sz++;    } u = Ch[u][c]; } Val[u] = 1;}    void init () {sz = 1;    memset (ch[0],0,sizeof (ch[0));    int m;    scanf ("%d", &m);    Char str[105];        while (m--) {scanf ("%s", str);    Insert (str);    }}int d[maxn];void find (int id, char* s) {D[id] = 0;    int u = 0;//int len = strlen (s);        for (int i = ID; s[i]; i++) {int c = idx (s[i]);        if (!ch[u][c]) return;        U = ch[u][c];    if (Val[u]) d[id] = (d[id]+d[i+1])%mod;    }}void Solve (char* s) {int len = strlen (s);    D[len] = 1; for (int i = len-1; I >= 0;    i--) {Find (I, s); } printf ("%d\n", D[0]);}    int main () {int cas = 0;    Char S[MAXN];        while (scanf ("%s", s)! = EOF) {init ();        printf ("Case%d:", ++cas);    Solve (s); } return 0;}

Attention:

The Find function must not strlen (), otherwise the timeout t_t. Because each call will be one length, time complexity is 0 (n*n);

UVA 1401 Remember The Word (Trie + DP)