fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. typedef long long lld;
  4. const int MOD = 1e9 + 7;
  5. const int MN = 2005;
  6. int n, m;
  7. int D[MN][MN];
  8.  
  9. void add(int& a, int b)
  10. {
  11. 	a += b;
  12. 	if(a >= MOD) a -= MOD;
  13. }
  14.  
  15. int solve(int open, int len)
  16. {
  17. 	if(open > 2000) return 0;
  18. 	if(len == 0){
  19. 		if(open == 0){
  20. 			return 1;
  21. 		}else{
  22. 			return 0;
  23. 		}
  24. 	}
  25. 	if(open < 0) return 0;
  26. 	int& ret = D[open][len];
  27. 	if(ret != -1) return ret;
  28. 	ret = 0;
  29. 	add(ret, solve(open - 1, len - 1));
  30. 	add(ret, solve(open + 1, len - 1));
  31. 	return ret;
  32. }
  33.  
  34. int main()
  35. {
  36. 	ios_base::sync_with_stdio(false);
  37. 	cin.tie(0);
  38. 	cin >> n >> m;
  39. 	string s;
  40. 	cin >> s;
  41. 	if(n % 2){
  42. 		cout << 0 << '\n';
  43. 		return 0;
  44. 	}
  45. 	int r = 0;
  46. 	int cnt = 0;
  47. 	for(int i = 0; i < s.size(); ++i){
  48. 		if(s[i] == '(') ++cnt;
  49. 		else --cnt;
  50. 		r = max(r, -cnt);
  51. 	}
  52. 	memset(D, -1, sizeof(D));
  53. 	int ans = 0;
  54. 	for(int i = r; i <= n - m; ++i){
  55. 		for(int j = 0; j <= n - m; ++j){
  56. 			add(ans, (lld)solve(i, j) * solve(i + cnt, n - m - j) % MOD);
  57. 		}
  58. 	}
  59. 	cout << ans << '\n';
  60. }
  61.  
Success #stdin #stdout 0.01s 19160KB
comments (?)
stdin
copy 
4 1
(
stdout
copy 
4
https://ideone.com/jo81en
codeforces round 343 div2 C
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!