Problem Set 3(Time Conversion)

Time Conversion:

Given a time in the 12-hour format with the suffix , either AM/PM, convert that  into a 24-hour format. 12-hour format is hours:minutes:seconds followed by AM or PM, where the hours range from 0 to 12, minutes range from 0 to 59, seconds range from 0 to 59.  24-hours format is hours:minutes and seconds , where hours range from 0 to 23, minutes range from 0 to 59, seconds range from 0 to 59. All the three components: hours, minutes, seconds are represented in the two digit format.

Note Midnight 12 o’clock is 12:00:00AM in the 12-hour format and it is 00:00:00 in 24- hour format. 12 Noon is 12:00:00PM in the 12-hour format and it is 12:00:00 in the 24- hour format.

For example, if input is 07:05:45PM then the output is 19:05:45 and if the input is 07:05:45AM then the output is 07:05:45.

Input format:

Time in 12-hour format with suffix, either  AM or PM

Output format:

Print time in 24-hour format

Boundary Conditions:

0 < hour, minute and seconds < 60

Meridium should be either “AM” or “PM”

Input:

Time in correct format from the user

Processing:

hrs = time[0:2]
minutes = time[3:5]
seconds = time[6:8]
AM_PM = time[8:10]
flag = True
if int(hrs) > 12:
    flag == False
if AM_PM == 'AM' and flag == True:
    if int(hrs) == 12:
        hrs = '0'
elif AM_PM == 'PM' and flag == True:
    if int(hrs) != 12:
        hrs = int(hrs) + 12
if int(minutes) > 60 or int(seconds) > 60:
    flag = False
if len(str(hrs)) != 2:
    hrs = '0' + str(hrs)
if len(str(minutes)) != 2:
    minutes = '0' + minutes
if len(str(seconds)) != 2:
    seconds = '0' + seconds

Output:

Display time in the 24 hour format

Algorithm:

Step1. Get the time in correct format from the user(time).

Step2. Split the time with respect to : and store each portion in hrs, minutes, seconds and AM_PM.

Step3. Check if hrs is greater than 12 if true then change flag to False else proceed to step4

Step4. Check if AM_PM is ‘AM’ and also check if flag is equal to True if both these are true then proceed to Step4.1 else proceed to step5

Step4.1 check if hrs is 12 if true then assign hrs as 0

Step5. Check if the element present in the third index of array is ‘PM’ and also check if flag is equal to True if both these are true then proceed to Step5.1 else proceed to step6

Step5.1 check if zeroth element of array is not equal to 12 if true then assign hrs as the sum of the integer conversion of hrs and 12

Step6. Check if the minutes and seconds are greater than 60 all the conditions are satisfied assign flag as false

Step7. If length of minutes string is less than two then concatenate it with a 0 at the front and do the same for seconds if length of the seconds string is less than 2

Step8. If flag is true then display the time 24 hr format else display invalid.

Step9. End

Program:

time = input()
hrs = time[0:2]
minutes = time[3:5]
seconds = time[6:8]
AM_PM = time[8:10]
flag = True
if int(hrs) > 12:
    flag == False
if AM_PM == 'AM' and flag == True:
    if int(hrs) == 12:
        hrs = '0'
elif AM_PM == 'PM' and flag == True:
    if int(hrs) != 12:
        hrs = int(hrs) + 12
if int(minutes) > 60 or int(seconds) > 60:
    flag = False
if len(str(hrs)) != 2:
    hrs = '0' + str(hrs)
if len(str(minutes)) != 2:
    minutes = '0' + minutes
if len(str(seconds)) != 2:
    seconds = '0' + seconds
if flag==True:
    print("%s:%s:%s"%(hrs,minutes,seconds))
else:

    print('Invalid')

Flowchart:

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