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  1. #include <bits/stdc++.h>
  2. #define int long long
  3. using namespace std;
  4. const int MOD = 1e9 + 7;
  5. map <pair <int, int>, int> memo;
  6.  
  7. int c(int n, int r) {
  8.     if (r < 0 || r > n) return 0;
  9.     if (r == 0 || r == n) return 1;
  10.     if (memo.find({n, r}) != memo.end()) return memo[{n, r}];
  11.     return memo[{n, r}] = (c(n - 1, r - 1) + c(n - 1, r)) % MOD;
  12. }
  13.  
  14. signed main() {
  15. 	ios_base::sync_with_stdio(0);
  16. 	cin.tie(0);
  17. 	int m, n;
  18. 	cin >> m >> n;
  19. 	cout << c(m + n - 1, m);
  20.     return 0;
  21. }
Success #stdin #stdout 0s 5316KB
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https://ideone.com/7QWbbS
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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