isValidBinaryString

isValidBinaryString.groovy

def isValidBinaryString(String list) {
  def total = list?.size()
  // TODO check one or more 0's or 1's with regex: \[0|1]+\g 🤔
  if (total == 0 || total % 2 != 0) {
    return false
  }
  // The number of 0's is equal to the number of 1's.
  if (list.findAll { it == '1' }?.size() != list.findAll { it == '0' }?.size()) {
    return false
  }
  
  // For every prefix of the binary string, the number of 1's should not be less than the number of 0's
  (0..(total - 1)).each {
    def prefix = list[0..it]
    if (prefix.findAll { it == '1' }?.size() >= prefix.findAll { it != '1' }?.size()) {
      return false
    }
  }
  
  true
}

println 'A- test 11010: ' + isValidBinaryString('11010') //false
println 'B- test 110010: ' + isValidBinaryString('110010')//true
println 'C- test empty: ' + isValidBinaryString('')//false
println 'C- test 110x10: ' + isValidBinaryString('110x10')//false