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| #include <bits/stdc++.h>
#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
struct PairHash {inline std::size_t operator()(const std::pair<int,int> & v) const {return v.first*31+v.second;}};
#define MAX_N 1010
#define INF 987654321
#define EPS 1e-9
#define ll long long
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vall3 vector<array<ll,3>>
#define all3 array<ll,3>
#define all5 array<ll,5>
#define vall5 vector<all5>
#define vll vector<ll>
#define vs vector<string>
#define usll unordered_set<ll>
#define uspll unordered_set<pll, PairHash>
#define vvs vector<vs>
#define vvll vector<vll>
#define all(a) begin(a), end(a)
using namespace std;
vvll freq;
ll fact[101010], mod = 1e9 + 7, inv[101010];
void initialize(string s) {
memset(fact, -1, sizeof fact);
memset(inv, -1, sizeof inv);
fact[0] = fact[1] = 1;
vll f(26);
freq.push_back(f);
for(auto& ch : s) {
f[ch-'a']++;
freq.push_back(f);
}
}
ll fac(ll n) {
if(fact[n] != -1) return fact[n];
return fact[n] = n * fac(n - 1) % mod;
}
vll query(ll l, ll r) {
vll res(26);
for(ll i = 0; i < 26; i++) {
res[i] = freq[r][i] - freq[l - 1][i];
}
return res;
}
ll _modpow(ll n, ll x) {
if(!x) return 1;
ll res = _modpow(n, x>>1);
res = res * res % mod;
if(x & 1) res = res * n % mod;
return res;
}
ll factmodpow(ll n, ll x) {
if(inv[n] != -1) return inv[n];
return inv[n] = _modpow(fac(n), mod - 2);
}
ll solve(int l, int r) {
vll f = query(l, r);
ll odd = 0, even = 0;
for(auto& c : f) {
if (c & 1) odd++;
even += c / 2;
}
odd = max(odd, 1ll);
ll res = fac(even) * odd % mod;
for(auto& c : f) {
ll e = c / 2;
if(!e) continue;
res = res * factmodpow(e, mod - 2) % mod;
}
return res;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
ll tc = 1;
for(ll i = 1; i <= tc; i++) {
string s;
ll q, l, r;
cin>>s>>q;
initialize(s);
for(ll j = 0; j < q; j++) {
cin>>l>>r;
cout<<solve(l, r)<<endl;
}
}
return 0;
}
|
