《Cracking the Coding Interview》——第6章：智力题——题目4

 1 // 6.4 There is an island with a bunch of people living there.
 2 // The strange thing is, any blue-eyed tourists must leave immediately when they find out they‘re blue-eyed.
 3 // Everyone can see others‘ eye colors, but not their own.
 4 // They know there‘ll be at least one blue-eyed tourists. If no more, the game ends.
 5 // Answer:
 6 //    Suppose there‘re n people and c are blue-eyed.
 7 //    If n == 1, that one will soon find out nobody else is blue-eyed, he‘ll leave on the 1st day.
 8 //    If n == 2, those two will see one blue-eyed, they are not sure if c == 1 or c == 2.
 9 //    But on the second day, when they still see each other, they know c == 2. Otherwise the one would have left. They‘ll leave on the 2nd day.
10 //    With mathematical induction, it can be proven that all the c blue-eyed will leave on the cth day together.
11 //    The most difficult part for me, is that when they can‘t be sure, they will simply stay. I thought every day there must‘ve been someone leaving.
12 int main()
13 {
14     return 0;
15 }