P4449 于神之怒加强版

R44323990

problem/P4449/P4449.cpp

@@ -0,0 +1,59 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const long long N = 6000010;
+const long long mod = 1000000007;
+
+long long n, m, k, t;
+long long ans, powk[N], vis[N], f[N], pri[N], tot;
+
+long long qpow(long long a, long long b) {
+    long long res = 1;
+    while (b) {
+        if (b & 1) res = res * a % mod;
+        a = a * a % mod;
+        b >>= 1;
+    }
+    return res;
+}
+
+void euler(long long n) {
+    f[1] = 1;
+    vis[1] = 1;
+    for (long long i = 2; i <= n; i++) {
+        if (!vis[i]) pri[++tot] = i, f[i] = (powk[i] - 1 + mod) % mod;
+        for (long long j = 1; j <= tot && i * pri[j] <= n; ++j) {
+            vis[i * pri[j]] = 1;
+            if (i % pri[j] == 0) {
+                f[i * pri[j]] = f[i] * powk[pri[j]] % mod;
+                break;
+            }
+            else {
+                f[i * pri[j]] = f[i] * f[pri[j]] % mod;
+            }
+        }
+    }
+}
+
+int main() {
+    cin >> t >> k;
+    for (long long i = 1; i <= 5000000; i++) {
+        powk[i] = qpow(i, k);
+    }
+    euler(5000000);
+    for (long long i = 1; i <= 5000000; i++) {
+        f[i] = (f[i] + f[i - 1]) % mod;
+    }
+    while (t--) {
+        cin >> n >> m;
+        ans = 0;
+        for (long long l = 1, r; l <= min(n, m); l = r + 1) {
+            r = min(n / (n / l), m / (m / l));
+            ans += (n / l) * (m / l) % mod * ((f[r] - f[l - 1] + mod) % mod) % mod;
+            ans %= mod;
+        }
+        cout << ans << endl;
+    }
+    return 0;
+}