I have a list of time string with different formats as shown

time = ["1:5 am", "1:35 am", "8:1 am", "9:14 am" "14:23 pm", "20:2 pm"]

dict = {'time': time}      
df = pd.DataFrame(dict)

and wanted to replace strings in list as shown below.

["01:05 am", "01:35 am", "08:01 am", "09:14 am" "14:23 pm", "20:02 pm"]

Not sure how to write a regex that format the string in DataFrame.