Look-and-say Sequence - Computer Program

Computer Program

The following Python code generates a look-and-say sequence using lazy evaluation:

def look_and_say(member): while True: yield member breakpoints = ( + [i for i in range(1, len(member)) if member != member] + ) groups = :breakpoints] for i in range(1, len(breakpoints))] member = ''.join(str(len(group)) + group for group in groups) # Print the 10-element sequence beginning with "1" sequence = look_and_say("1") for i in range(10): print sequence.next

The following Javascript code implementation using regular expression to generate first 10 elements of look-and-say sequence:

var number = "1"; var regexp = /(\d)\1*/g; for (var i = 0; i < 10; i++) { console.log(number); number = number.replace(regexp, function(fullmatch, symbol) { return fullmatch.length.toString + symbol; }); }