题解 | How Many Schemes-2019牛客暑期多校训练营第八场H题
作者：互联网
题目来源于牛客竞赛：https://ac.nowcoder.com/acm/contest/discuss
题目描述：
输入描述:
输出描述：
示例1：
题解：
代码：
#include <cstdio>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long LL;
#define N 4548 + 5
#define M 5000 + 5
#define S 40 + 5
#define LOGN 14
#define Mod 998244353
#define LIM 7985954824000000000LL
int n, m, q, tot, root, Head[N], Cur[N], Log[N], Upper[N], Dep[N], Go[N][LOGN];
struct Edge
{
int next, node;
string str;
}E[N << 1];
struct ACAM
{
int fail, flag, son[26];
}h[S];
struct Matrix
{
int r, c, num[S][S];
static Matrix IdelMatrix(int columns)
{
Matrix res;
res.r = 1, res.c = columns;
for (int i = 0; i < columns; i ++)
res.num[0][i] = (i == 0);
return res;
}
static Matrix Transfer(const string &str)
{
Matrix res;
res.r = res.c = tot + 1;
for (int i = 0; i < res.r; i ++)
for (int j = 0; j < res.c; j ++)
res.num[i][j] = 0;
for (int u = 0; u <= tot; u ++)
for (char c : str)
res.num[u][h[u].son[c - 'a']] ++;
return res;
}
Matrix operator * (const Matrix &obj) const
{
Matrix res;
res.r = r, res.c = obj.c;
for (int i = 0; i < res.r; i ++)
for (int j = 0, k; j < res.c; j ++)
{
LL tmp = 0;
for (int k = 0; k < c; k ++)
{
tmp += 1LL * num[i][k] * obj.num[k][j];
if (tmp >= LIM) tmp -= LIM;
}
res.num[i][j] = tmp % Mod;
}
return res;
}
};
vector<Matrix> Up[N], Down[N];
inline void addedge(int u, int v, string&& str)
{
static int cnt = 0;
E[++ cnt].next = Head[u], Head[u] = cnt;
E[cnt].node = v, E[cnt].str = str;
}
inline int Inc(int u, int v)
{
return u + v - (u + v >= Mod ? Mod : 0);
}
void BuildFail()
{
vector <int> Q;
for (int i = 0; i < 26; i ++)
if (h[0].son[i])
Q.push_back(h[0].son[i]);
for (int i = 0; i < Q.size(); i ++)
{
int u = Q[i], fail_u = h[u].fail;
for (int j = 0; j < 26; j ++)
{
if (!h[u].son[j])
h[u].son[j] = h[fail_u].son[j];
else
{
int d = h[u].son[j];
h[d].fail = h[fail_u].son[j];
h[d].flag |= h[h[d].fail].flag;
Q.push_back(d);
}
}
}
for (int u = 0; u <= tot; u ++)
if (h[u].flag)
for (int j = 0; j < 26; j ++)
h[u].son[j] = u;
}
void dfs(int rt, bool construct)
{
for (int i = 1; i <= n; i ++)
Cur[i] = Head[i], Go[i][0] = 0;
vector<int> Sta;
Sta.push_back(rt);
while (!Sta.empty())
{
int z = Sta.back();
if (Cur[z] && E[Cur[z]].node == Go[z][0])
Cur[z] = E[Cur[z]].next;
if (Cur[z])
{
int d = E[Cur[z]].node;
Dep[d] = Dep[z] + 1, Go[d][0] = z;
if (construct)
{
Up[d].resize(Upper[Dep[d]] + 1);
Down[d].resize(Upper[Dep[d]] + 1);
Up[d][0] = Down[d][0] = Matrix::Transfer(E[Cur[z]].str);
for (int j = 1, x = z; Go[x][j - 1]; x = Go[x][j - 1], j ++)
{
Go[d][j] = Go[x][j - 1];
if (j <= Upper[Dep[d]])
{
Up[d][j] = Up[d][j - 1] * Up[x][j - 1];
Down[d][j] = Down[x][j - 1] * Down[d][j - 1];
}
}
}
Sta.push_back(d);
Cur[z] = E[Cur[z]].next;
}
else Sta.pop_back();
}
}
void Handle()
{
static int Cnt[N];
for (int i = 0; i < n; i ++)
Cnt[i] = 0;
dfs(1, false);
int delta = 0, mx = 0;
for (int i = 1; i <= n; i ++)
Cnt[Dep[i]] ++, mx = max(mx, Dep[i]);
for (int w = 0; (1 << w) <= mx && w <= 9; w ++)
{
int cnt0 = 0, cnt1 = 0;
for (int i = 0; i <= mx; i ++)
{
if ((i & (1 << w) - 1) != delta)
continue ;
if ((i + delta >> w) & 1)
cnt1 += Cnt[i];
else cnt0 += Cnt[i];
}
if (cnt0 > cnt1)
delta += (1 << w);
}
if (delta)
{
root = n + delta;
for (int i = delta; i > 1; i --)
addedge(n + i, n + i - 1, "");
addedge(n + 1, 1, "");
}
else root = 1;
n += delta;
for (int i = 2; i <= n; i ++)
{
Log[i] = Log[i >> 1] + 1;
Upper[i] = (i & 1) ? 0 : Upper[i >> 1] + 1;
}
}
int LCA(int u, int v)
{
if (Dep[u] < Dep[v])
swap(u, v);
for (int t = Dep[u] - Dep[v]; t; t -= (t & -t))
u = Go[u][Log[t & -t]];
if (u == v) return u;
for (int i = Log[n]; Go[u][0] != Go[v][0]; i --)
if (Go[u][i] != Go[v][i])
u = Go[u][i], v = Go[v][i];
return Go[u][0];
}
vector<pair<int, int>> GetPath(int src, int dst)
{
vector<pair<int, int>> res;
for (int x = src, j; x != dst; x = Go[x][j])
{
for (j = Upper[Dep[x]]; Dep[x] - (1 << j) < Dep[dst]; j --) ;
res.emplace_back(x, j);
}
return res;
}
int main()
{
scanf("%d%d%d", &n, &m, &q);
for (int i = 1, u, v; i < n; i ++)
{
static char s[S];
static bool Flag[26];
scanf("%d%d%s", &u, &v, s);
for (int j = 0; j < 26; j ++)
Flag[j] = false;
addedge(u, v, s);
addedge(v, u, s);
}
Handle();
int tot_len = 0;
for (int i = 1; i <= m; i ++)
{
static char s[S];
scanf("%s", s);
int u = 0;
for (int j = 0; s[j]; j ++)
{
tot_len ++;
int d = s[j] - 'a';
if (!h[u].son[d])
h[u].son[d] = ++ tot;
u = h[u].son[d];
}
h[u].flag = true;
}
BuildFail();
dfs(root, true);
for (int i = 1, u, v; i <= q; i ++)
{
scanf("%d%d", &u, &v);
int lca = LCA(u, v);
Matrix f = Matrix::IdelMatrix(tot + 1);
vector<pair<int, int>> u_path = GetPath(u, lca);
vector<pair<int, int>> v_path = GetPath(v, lca);
for (const pair<int, int> &p : u_path)
f = f * Up[p.first][p.second];
reverse(v_path.begin(), v_path.end());
for (const pair<int, int> &p : v_path)
f = f * Down[p.first][p.second];
int res = 0;
for (int x = 0; x <= tot; x ++)
if (h[x].flag)
res = Inc(res, f.num[0][x]);
printf("%d\n", res);
}
return 0;
}
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标签：Schemes,Cur,How,int,题解,son,Dep,Go,fail 来源： https://blog.csdn.net/lastbye/article/details/100598885