fork download
copy 
  1. #include <iomanip>
  2. #include <iostream>
  3. #include <numeric>
  4. #include <string>
  5.  
  6. using namespace std;
  7.  
  8. bool foo(const string& context, const size_t pos) {
  9.   const auto it = next(cbegin(context), pos);
  10.   const auto before = accumulate(cbegin(context), it, 0, [](const auto output, const auto input) {
  11.     if(input == '{') {
  12.       return output + 1;
  13.     }
  14.     else if(input == '}' && output > 0) {
  15.       return output - 1;
  16.     }
  17.     else {
  18.       return output;
  19.     }
  20.   });
  21.   const auto after = accumulate(it, cend(context), 0, [](const auto output, const auto input) {
  22.     if(input == '{') {
  23.       return output + 1;
  24.     }
  25.     else if(input == '}') {
  26.       return output - 1;
  27.     }
  28.     else {
  29.       return output;
  30.     }
  31.   });
  32.  
  33.   return before + after >= 0;
  34. }
  35.  
  36. int main() {
  37.   cout << boolalpha;
  38.  
  39.   for(const auto& test : { ""s, "{"s, "}"s, "{}"s, "{{}}"s, "}{}"s, "{{}"s, "{}}"s, "{}{"s }) {
  40.     cout << test << endl;
  41.  
  42.     for(size_t i = 0; i <= test.size(); ++i) {
  43.       cout << '\t' << i << ": " << foo(test, i) << endl;
  44.     }
  45.   }
  46. }
Success #stdin #stdout 0s 15240KB
comments ()
stdin
copy 
Standard input is empty
stdout
copy 
	0: true
{
	0: true
	1: true
}
	0: false
	1: true
{}
	0: true
	1: true
	2: true
{{}}
	0: true
	1: true
	2: true
	3: true
	4: true
}{}
	0: false
	1: true
	2: true
	3: true
{{}
	0: true
	1: true
	2: true
	3: true
{}}
	0: false
	1: false
	2: false
	3: true
{}{
	0: true
	1: true
	2: true
	3: true
https://ideone.com/T6E09V
language:
C++14 (gcc 8.3)
created:
6 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!