#include<bits/stdc++.h>
using namespace std;
//#include<ext/pb_ds/assoc_container.hpp>
//#include<ext/pb_ds/tree_policy.hpp>
//
// #pragma GCC optimize("unroll-loops")
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("-O3")
// #pragma GCC optimize("no-stack-protector")
// #pragma GCC optimize("fast-math")
//#define LOCAL
#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifndef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
*this << "[";
for (auto it = d.b; it != d.e; ++it)
*this << ", " + 2 * (it == d.b) << *it;
ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define fi first
#define f first
#define se second
#define s second
#define vi_a vector<int>a;
#define p_b push_back
////////////////////////////////???????????????CHECK THIS OUT???????????????//////////////////////////////
#define ll long long
typedef unsigned long long ull;
////////////////////////////////???????????????CHECK THIS OUT???????????????//////////////////////////////
#define ld long double
#define pll pair<ll,ll>
#define pii pair<int,int>
#define m_p make_pair
#define fast_io cin.tie(0);cout.tie(0);ios_base::sync_with_stdio(0);
#define all(x) x.begin(),x.end()
#define getfiles ifstream cin("input.txt");ofstream cout("output.txt");
#define pw(x) (1ll << x)
#define sz(x) (int)x.size()
#define endl "\n"
#define rall(x) x.rbegin(),x.rend()
#define len(a) (ll)a.size()
#define rep(x,l,r) for(ll x=l;x<r;x++)
//using namespace __gnu_pbds;
ld eps = (ld)1 / 1e6;
const ld pi=3.14159265359;
ll inf = 1e18,mod1=1e9+7;
ll sqr(ll a) { return a * a; }
ll qb(ll a) { return a * a * a; }
ll gcd(ll a, ll b) { return !a ? b : gcd(b % a, a); }
ll binpow(ll a, ll b, ll mod) { return b ? (b % 2 ? (a * (sqr(binpow(a, b / 2, mod)) % mod)) % mod : sqr(binpow(a, b / 2, mod)) % mod) : 1; }
ll binmult(ll a, ll b, ll mod) { return b ? (b % 2 ? (2 * binmult(a, b / 2, mod) + a) % mod : (2 * binmult(a, b / 2, mod)) % mod) : 0; }
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
const ll R=1e4;
const ll tx[4]={0,0,-1,1};
const ll ty[4]={-1,1,0,0};
const char rev_to[4]={'E','W','N','S'};
const int N=2e3+1;
const int M=1e9+7;
//typedef tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update> st;
auto rnd=bind(uniform_int_distribution<ll>(1,125),mt19937(time(0)));
void bad(){
cout<<-1;
exit(0);
}
string s;
vector<int> pos[26];
int prec[N][26][26];
int f[N],inv[N];
void init(){
f[0]=1;for(int i=1;i<N;i++) f[i]=(f[i-1]*1ll*i)%M;
inv[N-1]=binpow(f[N-1],M-2,M);for(int i=N-2;i>=0;i--) inv[i]=(inv[i+1]*1ll*(i+1))%M;
}
ll C(int n,int k){
if(!k) return 1;
return 1ll*f[n]*inv[k]%M*inv[n-k]%M;
}
int n,q;
signed main()
{
fast_io;
cin>>s;n=sz(s);
for(int i=0;i<n;i++){
pos[s[i]-'a'].p_b(i);
}
init();
for(int le=2;le<=sz(s);le++){
for(int ch1=0;ch1<26;ch1++){
for(auto &z : pos[ch1]){
if(z+2<le) continue;
for(int ch2=0;ch2<26;ch2++){
int poss=upper_bound(all(pos[ch2]),z)-pos[ch2].begin();
if(poss==sz(pos[ch2])) continue;
prec[le][ch1][ch2]=( prec[le][ch1][ch2]+(1ll*C(z,le-2)*(sz(pos[ch2])-poss)%M))%M;
// debug()<<imie(C(z,le-2))<<imie(sz(pos[ch2])-poss);
}
}
}
}
cin>>q;
while(q--){
int a; char b,c;
cin>>a;cin>>b>>c;
cout<<prec[a][b-'a'][c-'a']<<endl;
}
return 0;
}
/*
0 0 0
2 1 3
3 2 7
1 3 8
1 4 2
3 5 3
/
*/
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
6 ms |
768 KB |
Output is correct |
| 2 |
Correct |
4 ms |
640 KB |
Output is correct |
| 3 |
Correct |
5 ms |
640 KB |
Output is correct |
| 4 |
Correct |
7 ms |
768 KB |
Output is correct |
| 5 |
Correct |
34 ms |
2740 KB |
Output is correct |
| 6 |
Correct |
37 ms |
2936 KB |
Output is correct |
| 7 |
Correct |
37 ms |
2560 KB |
Output is correct |
| 8 |
Correct |
28 ms |
2432 KB |
Output is correct |
| 9 |
Correct |
1719 ms |
14712 KB |
Output is correct |
| 10 |
Correct |
1724 ms |
14860 KB |
Output is correct |
