validTime.R

# Check if the given string is a correct time representation of the 24-hour clock.
# 
# Example
# 
# For time = "13:58", the output should be
# validTime(time) = true;
# For time = "25:51", the output should be
# validTime(time) = false;
# For time = "02:76", the output should be
# validTime(time) = false.
# 
# Input/Output
# 
# [execution time limit] 5 seconds (r)
# 
# [input] string time
# 
# A string representing time in HH:MM format. It is guaranteed that the first two characters, as well as the last two characters, are digits.
# 
# [output] boolean
# 
# true if the given representation is correct, false otherwise.

validTime <- function(time) {
  if (between(as.numeric(substr(time,1,2)),0,23) & (between(as.numeric(substr(time,4,5)),0,59))) {
    return(TRUE)
  } else {
    return(FALSE)
  }
}