Codeforces 893E 数论

#include <bits/stdc++.h>using namespace std;typedef long long ll;typedef vector<int> VI;const int N = 1000050;const ll mod = 1e9 + 7;template<class T>T read(){    T x = 0, f = 1; char ch = getchar();    while(ch < '0' || ch > '9')  { if(ch == '-') f = -1; ch = getchar();}    while(ch >= '0' && ch<= '9') { x = 10 * x + ch - '0'; ch = getchar();}    return x * f;}ll fac[N], inv[N], q[N];VI vec[N];ll qpow(ll a, ll b, ll p){    ll res = 1 % p;    while(b)    {        if(b & 1) res = res * a % p;        a = a * a % p;        b >>= 1;    }    return res;}void init(){    fac[1] = 1;    for(int i = 2; i < N; ++i) fac[i] = fac[i - 1] * i % mod;    q[0] = 1;    for(int i = 1; i < N; ++i) q[i] = q[i - 1] * 2 % mod;    inv[N - 1] = qpow(fac[N - 1], mod - 2, mod);    for(int i = N - 2; i >= 0; --i) inv[i] = inv[i + 1] * (i + 1) % mod;    for(int i = 2; i < N; ++i)    {        if(vec[i].empty())            for(int j = i; j < N; j += i)                vec[j].push_back(i);    }}ll C(int m, int n){    return fac[m] * inv[n] % mod * inv[m - n] % mod;}int main(){    init();    int T = read<int>();    while(T--)    {        int n = read<int>(), k = read<int>();        ll ans = 1;        for(auto u : vec[n])        {            int tmp = n, cnt = 0;            while(tmp % u == 0)            {                ++cnt;                tmp /= u;            }            ans = ans * C(cnt + k - 1, k - 1) % mod;;        }        ans = ans * q[k - 1] % mod;        printf("%I64d\n", ans);    }    return 0;}