函数板子

gcd

LL gcd(LL a, LL b){
	return (a % b == 0) ? b : gcd(b, a % b);
}

快速幂

LL qp(LL a, LL b){
	if (b == 0) return 1;
	LL ans = 1;
	while (b != 0){
		if (b & 1) ans = (ans * a) % mod;
		b >>= 1;
		a = (a * a) % mod;
	}
	return ans;
}

sqrt

LL mySqrt(LL x){
	LL k = sqrt(x) - 1;
	while ((k + 1) * (k + 1) <= x) k++;
	return k;
}

unique

vector  :: iterator unique(vector  &a){
	LL j = 0;
	for (LL i = 0; i < a.size(); i++)
		if (!i || a[i] != a[i - 1])
			a[j++] = a[i];
	return a.begin() + j;
}