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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. static const uint32_t MOD = (1u << 30);
  5.  
  6. uint32_t divisors_count(uint64_t n) {
  7.     static unordered_map<uint64_t, uint32_t> memo;
  8.     auto it = memo.find(n);
  9.     if (it != memo.end()) return it->second;
  10.  
  11.     uint64_t m = n;
  12.     uint32_t ans = 1;
  13.     for (uint64_t p = 2; p * p <= m; ++p) {
  14.         if (m % p == 0) {
  15.             int e = 0;
  16.             while (m % p == 0) { m /= p; ++e; }
  17.             ans = (uint64_t)ans * (e + 1) % MOD;
  18.         }
  19.     }
  20.     if (m > 1) ans = (uint64_t)ans * 2 % MOD;
  21.  
  22.     memo[n] = ans;
  23.     return ans;
  24. }
  25.  
  26. int main() {
  27.     ios::sync_with_stdio(false);
  28.     cin.tie(nullptr);
  29.  
  30.     long long a, b, c;
  31.     if (!(cin >> a >> b >> c)) return 0;
  32.  
  33.     uint32_t res = 0;
  34.  
  35.     if (a > b) swap(a, b);
  36.     if (b > c) swap(b, c);
  37.     if (a > b) swap(a, b);
  38.  
  39.     for (long long x = 1; x <= a; ++x) {
  40.         for (long long y = 1; y <= b; ++y) {
  41.             uint64_t xy = (uint64_t)x * (uint64_t)y;
  42.             for (long long z = 1; z <= c; ++z) {
  43.                 uint64_t n = xy * (uint64_t)z;
  44.                 res += divisors_count(n);
  45.             }
  46.         }
  47.     }
  48.  
  49.     cout << (res & (MOD - 1)) << '\n';
  50.     return 0;
  51. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/GSM6G4
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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