final solution: finds total days between given dates

Udacity Data Structure and Algorithms Nanodegree/Introduction/daysBetweenDatesFinal.py

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+
+# Use Dave's suggestions to finish your daysBetweenDates
+# procedure. It will need to take into account leap years
+# in addition to the correct number of days in each month.
+
+
+def leapYear(year):
+    if year % 400 == 0:
+        return True
+    if year % 100 == 0:
+        return False
+    if year % 4 == 0:
+        return True
+    return False
+
+
+def daysInMonth(year, month):
+    if month == 1 or month == 3 or month == 5 or month == 7 or month == 8 or month == 10 or month == 12:
+        return 31
+    else:
+        if month == 2:
+            if leapYear(year):
+                return 29
+            else:
+                return 28
+        else:
+            return 30
+
+
+def nextDay(year, month, day):
+    """Simple version: assume every month has 30 days"""
+    if day < daysInMonth(year, month):
+        return year, month, day + 1
+    else:
+        if month == 12:
+            return year + 1, 1, 1
+        else:
+            return year, month + 1, 1
+
+
+def dateIsBefore(year1, month1, day1, year2, month2, day2):
+    """Returns True if year1-month1-day1 is before year2-month2-day2. Otherwise, returns False."""
+    if year1 < year2:
+        return True
+    if year1 == year2:
+        if month1 < month2:
+            return True
+        if month1 == month2:
+            return day1 < day2
+    return False
+
+
+def daysBetweenDates(year1, month1, day1, year2, month2, day2):
+    """Returns the number of days between year1/month1/day1
+       and year2/month2/day2. Assumes inputs are valid dates
+       in Gregorian calendar."""
+    # program defensively! Add an assertion if the input is not valid!
+
+    assert not dateIsBefore(year2, month2, day2, year1, month1, day1)
+
+    days = 0
+
+    while dateIsBefore(year1, month1, day1, year2, month2, day2):
+        year1, month1, day1 = nextDay(year1, month1, day1)
+        days += 1
+    return days
+
+
+def test():
+    test_cases = [((2012, 1, 1, 2012, 2, 28), 58),
+                  ((2012, 1, 1, 2012, 3, 1), 60),
+                  ((2011, 6, 30, 2012, 6, 30), 366),
+                  ((2011, 1, 1, 2012, 8, 8), 585),
+                  ((1900, 1, 1, 1999, 12, 31), 36523)]
+
+    for (args, answer) in test_cases:
+        result = daysBetweenDates(*args)
+        if result != answer:
+            print("Test with data:", args, "failed")
+        else:
+            print("Test case passed!")
+
+
+test()