C++ 解法, 执行用时: 312ms, 内存消耗: 45836K, 提交时间: 2021-11-01 22:24:11

#include<bits/stdc++.h>
#include<unordered_map>
using namespace std;
const int mod = 1e9 + 7;
const int maxn = 5000001;
int pri[maxn], cnt;
bool vis[maxn];
int f[maxn], g[maxn];
void init() {
	f[1] = g[1] = 1;
	for (int i = 2; i < maxn; i++) {
		if (!vis[i])
			pri[cnt++] = i, f[i] = i - 1, g[i] = i - 2;
		for (int j = 0; j < cnt && i * pri[j] < maxn; j++) {
			vis[i * pri[j]] = 1;
			if (i % pri[j])
				f[i * pri[j]] = f[i] * f[pri[j]], g[i * pri[j]] = g[i] * g[pri[j]];
			else {
				f[i * pri[j]] = f[i] * pri[j];
				if (i / pri[j] % pri[j])
					g[i * pri[j]] = g[i / pri[j]] * f[pri[j]] * f[pri[j]];
				else
					g[i * pri[j]] = g[i] * pri[j];
				break;
			}
		}
	}
	for (int i = 2; i < maxn; i++) {
		f[i] += f[i - 1],g[i]+=g[i-1];
		if (f[i] >= mod)
			f[i] -= mod;
		if (g[i] >= mod)
			g[i] -= mod;
	}
}
map<int, int>mf, mg;
int djsf(int n) {
	if (n < maxn)
		return f[n];
	if (mf.count(n))
		return mf[n];
	long long ans = 1ll * n * (n + 1) / 2 % mod;
	for (int l = 2, r; l <= n; l = r + 1)
		r = n / (n / l), ans -= 1ll * (r - l + 1) * djsf(n / l) % mod;
	return mf[n] = ans % mod;
}
int djsg(int n) {
	if (n < maxn)
		return g[n];
	if (mg.count(n))
		return mg[n];
	long long ans = djsf(n);
	for (int l = 2, r; l <= n; l = r + 1)
		r = n / (n / l), ans -= 1ll * (r - l + 1) * djsg(n / l) % mod;
	return mg[n] = ans % mod;
}
signed main() {
	init();
	int n, m;
	cin >> n >> m;
	long long ans = 0;
	for (int l = 1, r; l <= min(n, m); l = r + 1)
		r = min(n / (n / l), m / (m / l)), ans += 1ll * n / l * (m / l) % mod * (djsg(r) - djsg(l - 1)) % mod;
	cout << (ans % mod + mod) % mod;
}