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  1. #include <iostream>
  2. #include <vector>
  3. #include <queue>
  4. #include <string>
  5. #include <algorithm>
  6. #include <utility>
  7. #include <cmath>
  8. using namespace std;
  9.  
  10. typedef pair<int, int> P;
  11. typedef long long ll;
  12.  
  13. const int INF = 1000000007;
  14.  
  15. ll factorial(ll n){
  16.     if(n == 1){
  17.         return 1;
  18.     }
  19.     return ( n * factorial(n-1) ) % INF;
  20. }
  21. int main(void){
  22.     ll n, m;
  23.     cin >> n >> m;
  24.     if(abs(n-m) > 1){
  25.         cout << "0" << endl;
  26.         return 0;
  27.     }
  28.     ll sum = ((factorial(n) % INF ) * (factorial(m) % INF)) % INF;
  29.     ll ans;
  30.     if(n == m){
  31.         ans = (sum*2) % INF;
  32.     }else{
  33.         ans = sum;
  34.     }
  35.     cout << ans << endl;
  36.  
  37.     return 0;
  38. }
Success #stdin #stdout 0s 17496KB
comments (?)
stdin
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100000 100000
stdout
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530123477
https://ideone.com/26IzAa
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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