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  1. #include <algorithm>
  2. #include <iostream>
  3. #include <iterator>
  4. #include <string>
  5.  
  6. namespace
  7. {
  8.     /// {п4,a}b4c{2,p} -> aaaab4cpp
  9.     template<class InputIt, class OutputIt>
  10.     OutputIt rle_decode(InputIt first, InputIt last, OutputIt d_first)
  11.     {
  12.       while(first != last) {
  13.         if (*first != '{') {
  14.           *d_first++ = *first++; // copy the input to the output as is
  15.         }
  16.         else { // decode {count,char} RLE run
  17.           ++first; // skip {
  18.  
  19.           // read count
  20.           uintmax_t count = 0;
  21.           for ( ; first != last && '0' <= *first && *first <= '9'; ++first )
  22.             count += 10 * count + (*first - '0'); //NOTE: ignore overflow
  23.  
  24.           if (first == last || *first++ != ',' || first == last)
  25.             throw std::invalid_argument("missing comma or char in {count,char}");
  26.  
  27.           // output current character *count* times
  28.           d_first = std::fill_n(d_first, count, *first++);
  29.  
  30.           if (first == last || *first++ != '}')
  31.             throw std::invalid_argument("expected '}'");
  32.         }
  33.       }
  34.       return d_first;
  35.     }
  36.   }
  37.  
  38. int main()
  39. {
  40.   std::string text = "{4,a}b4c{2,p}";
  41.   std::string s;
  42.   rle_decode(std::begin(text), std::end(text), std::back_inserter(s));
  43.   std::cout << s << '\n';
  44.  
  45.   rle_decode(std::begin(text), std::end(text), std::ostream_iterator<char>(std::cout));
  46.   std::cout << '\n';
  47.  
  48.   std::istream_iterator<char> chars{std::cin}, eof;
  49.   rle_decode(chars, eof, std::ostream_iterator<char>(std::cout));
  50.   std::cout << '\n';
  51. }
  52.  
Success #stdin #stdout 0s 15232KB
comments (?)
stdin 
{123,a}b{1,c}
stdout 
aaaab4cpp
aaaab4cpp
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabc
https://ideone.com/d1gknK
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
secret

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