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  1. #include<iostream>
  2. #include<cmath>
  3. #include<algorithm>
  4. #include<iomanip>
  5. #include<climits>
  6. #include<numeric>
  7. #include<set>
  8. #include<sstream>
  9. #include<map>
  10. #include<vector>
  11. #include<string>
  12. #include<regex>
  13.  
  14. using namespace std;
  15.  
  16. const long long MOD = (long long)(1e9 + 7);
  17.  
  18. vector<string> split(const string& haystack, const string& needle) {
  19. 	vector<string> result;
  20. 	size_t start_pos = 0;
  21. 	size_t found_pos = haystack.find(needle, start_pos);
  22. 	while (found_pos != string::npos) {
  23. 		size_t count = found_pos - start_pos;
  24. 		string token = haystack.substr(start_pos, count);
  25. 		if (!token.empty()) {
  26. 			result.push_back(token);
  27. 		}
  28. 		start_pos = found_pos + needle.length();
  29. 		found_pos = haystack.find(needle, start_pos);
  30. 	}
  31.  
  32. 	string last_token = haystack.substr(start_pos);
  33. 	if (!last_token.empty()) {
  34. 		result.push_back(last_token);
  35. 	}
  36. 	return result;
  37. }
  38.  
  39. int main() {
  40. 	string s;cin >> s;
  41. 	int max_length = 0;
  42. 	map<int, int> prefix;
  43. 	int sum = 0;
  44. 	for (int i = 0;i < s.length();i++) {
  45. 		if (s[i] == '1') {
  46. 			sum++;
  47. 		}
  48. 		else {
  49. 			sum--;
  50. 		}
  51.  
  52. 		if (prefix.find(sum) != prefix.end()) {
  53. 			max_length = max(max_length, i - prefix[sum]);
  54. 		}
  55. 		else {
  56. 			prefix[sum] = i;
  57. 		}
  58.  
  59. 		if (sum == 0) {
  60. 			max_length = max(max_length, i + 1);
  61. 		}
  62. 	}
  63. 	cout << max_length;
  64. 	return 0;
  65. }
  66.  
  67.  
Success #stdin #stdout 0.01s 5324KB
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https://ideone.com/jW3uBJ
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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