辗转相除法
long long gcd(long long a, long long b){
if(a%b==0) {
return b;
}
return gcd(b,a%b);
}
埃氏筛法
int a[10000001];
void is_prime(){
a[1] = 1;
for(int i = 2; ii <= 10000001; i ++) {
if(a[i] == 0) {
for(int j = 2i; j <= 10000001; j += i) {
a[j] = 1;
}
}
}
}
队列
int q[100000];
int front = 0,rear = 0;
void pop(){
front++;
}
void push(){
rear++;
q[rear] = x;
}
int front(){
return q[front+1];
}
int rear(){
return q[rear];
}
bool empty(){
return front == rear;
}
int size(){
return rear - front;
}
