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Modulo.cpp
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Modulo.cpp
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const long long MOD = 1000000007;
long long modsub(long long a, long long b){
return (a % MOD - b % MOD + MOD) % MOD;
}
long long modpow(long long a, long long b){
long long ans = 1;
while (b > 0){
if (b % 2 == 1){
ans *= a;
ans %= MOD;
}
a *= a;
a %= MOD;
b /= 2;
}
return ans;
}
long long modinv(long long a){
return modpow(a, MOD - 2);
}
vector<long long> mf = {1};
vector<long long> mfi = {1};
long long modfact(int n){
if (mf.size() > n){
return mf[n];
} else {
for (int i = mf.size(); i <= n; i++){
long long next = mf.back() * i % MOD;
mf.push_back(next);
mfi.push_back(modinv(next));
}
return mf[n];
}
}
long long modfactinv(int n){
if (mfi.size() > n){
return mfi[n];
} else {
return modinv(modfact(n));
}
}
long long modbinom(int n, int k){
if (n < 0 || k < 0 || k > n){
return 0;
} else {
return modfact(n) * modfactinv(k) % MOD * modfactinv(n - k) % MOD;
}
}
long long modbinom2(long long n, int r){
long long ans = 1;
for (int i = 0; i < r; i++){
ans = ans * ((n - i) % MOD) % MOD;
ans = ans * modinv(i + 1) % MOD;
}
return ans;
}