hihocoder 1457 后缀自动机四·重复旋律7 ( 多串连接处理技巧 )

题目链接

分析 :

这道题对于单个串的用 SAM 然后想想怎么维护就行了

但是多个串下、可以先将所有的串用一个不在字符集( 这道题的字符集是 '0' ~ '9' )

链接起来、建立后缀自动机之后

在统计答案的时候直接忽略掉不合法的边集的状态转移即可

#include<bits/stdc++.h>
#define LL long long
#define ULL unsigned long long

#define scl(i) scanf("%lld", &i)
#define scll(i, j) scanf("%lld %lld", &i, &j)
#define sclll(i, j, k) scanf("%lld %lld %lld", &i, &j, &k)
#define scllll(i, j, k, l) scanf("%lld %lld %lld %lld", &i, &j, &k, &l)

#define scs(i) scanf("%s", i)
#define sci(i) scanf("%d", &i)
#define scd(i) scanf("%lf", &i)
#define scIl(i) scanf("%I64d", &i)
#define scii(i, j) scanf("%d %d", &i, &j)
#define scdd(i, j) scanf("%lf %lf", &i, &j)
#define scIll(i, j) scanf("%I64d %I64d", &i, &j)
#define sciii(i, j, k) scanf("%d %d %d", &i, &j, &k)
#define scddd(i, j, k) scanf("%lf %lf %lf", &i, &j, &k)
#define scIlll(i, j, k) scanf("%I64d %I64d %I64d", &i, &j, &k)
#define sciiii(i, j, k, l) scanf("%d %d %d %d", &i, &j, &k, &l)
#define scdddd(i, j, k, l) scanf("%lf %lf %lf %lf", &i, &j, &k, &l)
#define scIllll(i, j, k, l) scanf("%I64d %I64d %I64d %I64d", &i, &j, &k, &l)

#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define lowbit(i) (i & (-i))
#define mem(i, j) memset(i, j, sizeof(i))

#define fir first
#define sec second
#define VI vector<int>
#define ins(i) insert(i)
#define pb(i) push_back(i)
#define pii pair<int, int>
#define VL vector<long long>
#define mk(i, j) make_pair(i, j)
#define all(i) i.begin(), i.end()
#define pll pair<long long, long long>

#define _TIME 0
#define _INPUT 0
#define _OUTPUT 0
clock_t START, END;
void __stTIME();
void __enTIME();
void __IOPUT();
using namespace std;

const LL mod = (LL)1e9 + 7;

struct SAM
{
    static const int MAXN = ((int)1e6 + 10)<<1;//大小为字符串长度两倍
    static const int LetterSize = 26;

    int tot, last, ch[MAXN][LetterSize], fa[MAXN], len[MAXN];
    int tpSum[MAXN], tp[MAXN], cnt[MAXN]; //tpSum,tp用于拓扑排序，tp为排序后的数组

    void init(void){
        last = tot = 1;
        len[1] = 0;
        memset( ch[1], 0, sizeof ch[1]);
    }

    void add( int x){
        int p = last, np = last = ++tot;
        len[np] = len[p] + 1, cnt[last] = 1;
        memset( ch[np], 0, sizeof ch[np]);
        while( p && !ch[p][x]) ch[p][x] = np, p = fa[p];
        if( p == 0)
            fa[np] = 1;
        else
        {
            int q = ch[p][x];
            if( len[q] == len[p] + 1)
                fa[np] = q;
            else
            {
                int nq = ++tot;
                memcpy( ch[nq], ch[q], sizeof ch[q]);
                len[nq] = len[p] + 1, fa[nq] = fa[q], fa[q] = fa[np] = nq;
                while( p && ch[p][x] == q)  ch[p][x] = nq, p = fa[p];
            }
        }
    }

    void toposort(void){
        for(int i = 1; i <= len[last]; i++)   tpSum[i] = 0;
        for(int i = 1; i <= tot; i++)   tpSum[len[i]]++;
        for(int i = 1; i <= len[last]; i++)   tpSum[i] += tpSum[i-1];
        for(int i = 1; i <= tot; i++)   tp[tpSum[len[i]]--] = i;
        //for(int i = tot; i; i--)   cnt[fa[tp[i]]] += cnt[tp[i]];
    }

    LL sum[MAXN];
    LL GetAns(){

        mem(cnt, 0);

        cnt[1] = 1;

        for(int i=1; i<=tot; i++){
            int cur = tp[i];

            if(!cnt[cur]) continue;

            for(int c=0; c<10; c++){
                int nxt = ch[cur][c];
                if(nxt){
                    cnt[nxt] = (cnt[nxt] + cnt[cur]) % mod;
                    sum[nxt] = (sum[nxt] + (sum[cur] * 10 % mod + 1LL * c * cnt[cur] % mod) % mod) %mod;
                }
            }
        }

        LL ret = 0;
        for(int i=1; i<=tot; i++) ret = (ret + sum[i]) % mod;

        return ret;
    }

} sam;

int n;
char str[(int)1e6 + 10];

int main(void){__stTIME();__IOPUT();

    sci(n);

    sam.init();

    for(int i=0; i<n; i++){
        scs(str);

        int len = strlen(str);

        for(int j=0; j<len; j++)
            sam.add(str[j] - '0');

        if(i != n-1)
            sam.add(10);
    }

    sam.toposort();

    printf("%lld
", sam.GetAns());


__enTIME();return 0;}


void __stTIME()
{
    #if _TIME
        START = clock();
    #endif
}

void __enTIME()
{
    #if _TIME
        END = clock();
        cerr<<"execute time = "<<(double)(END-START)/CLOCKS_PER_SEC<<endl;
    #endif
}

void __IOPUT()
{
    #if _INPUT
        freopen("in.txt", "r", stdin);
    #endif
    #if _OUTPUT
        freopen("out.txt", "w", stdout);
    #endif
}