[BZOJ2820]YY的GCD

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <algorithm>
using namespace std;

const int BufferSize = 1 << 16;
char buffer[BufferSize], *Head, *Tail;
inline char Getchar() {
	if(Head == Tail) {
		int l = fread(buffer, 1, BufferSize, stdin);
		Tail = (Head = buffer) + l;
	}
	return *Head++;
}
int read() {
	int x = 0, f = 1; char c = Getchar();
	while(!isdigit(c)){ if(c == ‘-‘) f = -1; c = Getchar(); }
	while(isdigit(c)){ x = x * 10 + c - ‘0‘; c = Getchar(); }
	return x * f;
}

#define maxn 10000010
#define LL long long

int prime[maxn], cp, mu[maxn], f[maxn], sf[maxn];
bool vis[maxn];
void init() {
	mu[1] = 1;
	for(int i = 2; i < maxn; i++) {
		if(!vis[i]) prime[++cp] = i, mu[i] = -1;
		for(int j = 1; i * prime[j] < maxn && j <= cp; j++) {
			vis[i*prime[j]] = 1;
			if(i % prime[j] == 0){ mu[i*prime[j]] = 0; break; }
			mu[i*prime[j]] = -mu[i];
		}
	}
	for(int i = 1; i <= cp; i++)
		for(int j = 1; prime[i] * j < maxn; j++) f[j*prime[i]] += mu[j];
	for(int i = 1; i < maxn; i++) sf[i] = sf[i-1] + f[i];
	return ;
}

int main() {
	init();
	
	int T = read();
	while(T--) {
		int n = read(), m = read();
		if(n > m) swap(n, m);
		LL ans = 0;
		for(int i = 1, lst; i <= n; i = lst + 1) {
			lst = min(n / (n / i), m / (m / i));
			ans += (LL)(n / i) * (m / i) * (sf[lst] - sf[i-1]);
		}
		printf("%lld\n", ans);
	}
	
	return 0;
}