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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. const int N = 1e3 + 5;
  6. const int MAX = 1e6 + 5;
  7. const long long M = 1e9 + 7;
  8.  
  9. int tc;
  10. int n, k[N];
  11. long long pre[N];
  12. long long fac[MAX], inv[MAX];
  13.  
  14. long long modpow(long long x, long long y, long long p) {
  15.     long long ret = 1;
  16.     while (y > 0) {
  17.         if (y % 2 == 1) {
  18.             ret = (ret * x) % M;
  19.         }
  20.         y /= 2;
  21.         x = (x * x) % M;
  22.     }
  23.     return ret;
  24. }
  25.  
  26. long long C(long long a, long long b) {
  27.     if (a < b) return 0;
  28.     long long ret = (fac[a] * inv[b]) % M;
  29.     ret = (ret * inv[a - b]) % M;
  30.     return ret;
  31. }
  32.  
  33. int main() { 
  34.     ios_base::sync_with_stdio(0);
  35.     cin.tie(0);
  36.     cout.tie(0);
  37.  
  38.     fac[0] = inv[0] = 1;
  39.     for (int i = 1; i < MAX; i++) {
  40.         fac[i] = (i * fac[i - 1]) % M;
  41.         inv[i] = modpow(fac[i], M - 2, M);
  42.     }
  43.     cin >> tc;
  44.     for (int tt = 1; tt <= tc; tt++) {
  45.         cin >> n;
  46.         for (int i = 1; i <= n; i++) {
  47.             cin >> k[i];
  48.             pre[i] = k[i] + pre[i - 1];
  49.         }
  50.         long long res = 1;
  51.         for (int i = n; i >= 1; i--) {
  52.             res = (res * C(pre[i] - 1, k[i] - 1)) % M;
  53.         }
  54.         cout << "Case " << tt << ": ";
  55.         cout << res << '\n';
  56.     }
  57.  
  58.     return 0;
  59. }
Success #stdin #stdout 0.11s 19092KB
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https://ideone.com/1TqVYj
language:
C++ 4.3.2 (gcc-4.3.2)
created:
5 years ago
visibility:
secret

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