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UVA3942 Remember the Word

题意:输入一个字符串(l<300000),一个n(n<4000),接下来n个字符串(l<100),问能分解成几种字符串

题解:直接计算复杂度高,考虑DP,dp[i]代表以第i个字符开头的字符串分解的方案数,dp[i] = sum(dp[j+len]),len代表可以找到的字符串长度,多模式的字符串用到了char树,放在char树上跑一遍,找到以i+1开头的字符串复杂度,一开始写搜索。。后来发现复杂度过不去

#include <bits/stdc++.h>#define ll long long#define maxn 100*4000+10#define siz 26#define mod 20071027using namespace std;char s[300010], s1[110];ll l, dp[300010];struct Tire{    ll ch[maxn][siz];    ll val[maxn], sz;//节点总数    Tire(){sz = 1;memset(ch, 0, sizeof(ch));}    ll idx(char c){return c-a;}    void insert(char *s, ll v){        ll u = 0,n = strlen(s);        for(ll i=0;i<n;i++){            ll 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] = v;    }}Tir;int main(){    ll n, t = 0;    while(~scanf("%s", s)){        l = strlen(s);        memset(Tir.ch, 0, sizeof(Tir.ch));        Tir.sz = 1;        memset(dp, 0, sizeof(dp));        dp[l] = 1;        scanf("%lld", &n);        for(ll i=1;i<=n;i++){            scanf("%s", s1);            Tir.insert(s1, i);        }        for(int i=l-1;i>=0;i--){            int u = 0;            for(int j=i;j<l;j++){                if(Tir.ch[u][s[j]-a]==0) break;                u = Tir.ch[u][s[j]-a];                if(Tir.val[u]) dp[i] = (dp[i]+dp[j+1])%mod;            }        }        printf("Case %lld: %lld\n", ++t, dp[0]);    }    return 0;}

 

UVA3942 Remember the Word