Your mission

Implement roster_changes, which compares two rosters of names and counts the distinct names that stayed, left and joined.

See it in action

roster_changes(["Maya", "Odin", "Lea"], ["Lea", "Kofi", "Maya"])

(2, 1, 1)

roster_changes(["Tess", "Tess", "Bram"], ["Tess", "Ivo", "Ivo"])

(1, 1, 1)

roster_changes([], ["Nia"])

(0, 0, 1)

Your checklist

• before and after are lists of strings. Either can be empty, and a name can appear several times in the same list.
• Return a tuple (stayed, left, joined) of three int. stayed is the number of distinct names found in both lists.
• left is the number of distinct names found in before but not in after.
• joined is the number of distinct names found in after but not in before.
• Every string is a name, the empty string included. Two names are the same only when the strings are identical, case and spaces included.
• Do not modify before or after.

Your mission

Implement roster_changes, which compares two rosters of names and counts the distinct names that stayed, left and joined.

See it in action

roster_changes(["Maya", "Odin", "Lea"], ["Lea", "Kofi", "Maya"])

(2, 1, 1)

roster_changes(["Tess", "Tess", "Bram"], ["Tess", "Ivo", "Ivo"])

(1, 1, 1)

roster_changes([], ["Nia"])

(0, 0, 1)

Your checklist

• before and after are lists of strings. Either can be empty, and a name can appear several times in the same list.
• Return a tuple (stayed, left, joined) of three int. stayed is the number of distinct names found in both lists.
• left is the number of distinct names found in before but not in after.
• joined is the number of distinct names found in after but not in before.
• Every string is a name, the empty string included. Two names are the same only when the strings are identical, case and spaces included.
• Do not modify before or after.