1
00:00:00,000 --> 00:00:05,910
Might I call on, say, two volunteers to
kick us off with two, say, algorithms?

2
00:00:05,910 --> 00:00:07,170
Let's see.

3
00:00:07,170 --> 00:00:08,040
Over here?

4
00:00:08,040 --> 00:00:08,730
Yeah.

5
00:00:08,730 --> 00:00:12,570
And let's go over here
in front, if we may.

6
00:00:12,570 --> 00:00:14,420
Come on up.

7
00:00:14,420 --> 00:00:15,420
And what are your names?

8
00:00:15,420 --> 00:00:16,360
AUDIENCE: [? Nizari. ?]

9
00:00:16,360 --> 00:00:16,790
SPEAKER 1: Lizari?

10
00:00:16,790 --> 00:00:17,290
AUDIENCE: [? Nizari. ?]

11
00:00:17,290 --> 00:00:18,910
SPEAKER 1: [? Nizari. ?] OK, David.

12
00:00:18,910 --> 00:00:19,660
Nice to meet you.

13
00:00:19,660 --> 00:00:22,530
Come on up, [? Nizari. ?] And
over here, what's your name?

14
00:00:22,530 --> 00:00:23,320
AUDIENCE: Eric.

15
00:00:23,320 --> 00:00:24,160
SPEAKER 1: Eric, OK.

16
00:00:24,160 --> 00:00:24,660
David.

17
00:00:24,660 --> 00:00:26,070
And come on up, Brian, as well.

18
00:00:26,070 --> 00:00:27,530
Nice to meet you, Eric.

19
00:00:27,530 --> 00:00:29,420
Eric, [? Nizari. ?] [? Nizari, ?] Eric.

20
00:00:29,420 --> 00:00:30,750
[APPLAUSE]

21
00:00:30,750 --> 00:00:32,490
Come on over here.

22
00:00:32,490 --> 00:00:34,590
So you came on up the stage first.

23
00:00:34,590 --> 00:00:36,390
Would you like to go first or go second?

24
00:00:36,390 --> 00:00:37,130
AUDIENCE: I'll go second.

25
00:00:37,130 --> 00:00:38,370
SPEAKER 1: You're going to go second.

26
00:00:38,370 --> 00:00:39,120
So Eric, you're up first.

27
00:00:39,120 --> 00:00:40,450
Come on over here, if you would.

28
00:00:40,450 --> 00:00:45,120
So Eric, behind these seven doors we
have placed, in advance, the number 50.

29
00:00:45,120 --> 00:00:47,430
And we would simply
like you, the computer,

30
00:00:47,430 --> 00:00:50,420
to search this array for the number 50.

31
00:00:50,420 --> 00:00:52,300
AUDIENCE: Is it sorted?

32
00:00:52,300 --> 00:00:56,040
SPEAKER 1: I cannot answer
that question at this time.

33
00:00:56,040 --> 00:00:58,440
Go.

34
00:00:58,440 --> 00:01:00,150
Oh, and so that the
audience knows what's

35
00:01:00,150 --> 00:01:03,030
going on, if you wouldn't mind
taking the numbers out to see.

36
00:01:03,030 --> 00:01:04,220
AUDIENCE: This is seven.

37
00:01:04,220 --> 00:01:05,340
SPEAKER 1: Excellent.

38
00:01:05,340 --> 00:01:06,170
Not 50.

39
00:01:06,170 --> 00:01:08,020
AUDIENCE: Should I-- can I take it out?

40
00:01:08,020 --> 00:01:10,680
SPEAKER 1: At this point, yes,
you may do whatever you want now.

41
00:01:10,680 --> 00:01:12,450
Just find us 50.

42
00:01:12,450 --> 00:01:13,800
AUDIENCE: Two.

43
00:01:13,800 --> 00:01:14,720
[LAUGHTER]

44
00:01:14,720 --> 00:01:17,070
SPEAKER 1: Very good.

45
00:01:17,070 --> 00:01:18,260
AUDIENCE: One.

46
00:01:18,260 --> 00:01:20,830
SPEAKER 1: Nice.

47
00:01:20,830 --> 00:01:22,140
AUDIENCE: Six.

48
00:01:22,140 --> 00:01:24,950
SPEAKER 1: Very good.

49
00:01:24,950 --> 00:01:25,660
AUDIENCE: Three.

50
00:01:26,160 --> 00:01:26,820
SPEAKER 1: Nice.

51
00:01:26,820 --> 00:01:28,490
AUDIENCE: None of these are close to 50.

52
00:01:28,490 --> 00:01:30,480
SPEAKER 1: No, none of
them are close to 50.

53
00:01:30,480 --> 00:01:31,210
AUDIENCE: Four.

54
00:01:31,210 --> 00:01:32,670
SPEAKER 1: Four?

55
00:01:32,670 --> 00:01:34,600
And?

56
00:01:34,600 --> 00:01:35,580
AUDIENCE: 50!

57
00:01:35,580 --> 00:01:36,630
SPEAKER 1: Amazing!

58
00:01:36,630 --> 00:01:37,630
Very well done.

59
00:01:37,630 --> 00:01:39,820
[APPLAUSE]

60
00:01:40,640 --> 00:01:41,270
Very well done.

61
00:01:41,270 --> 00:01:43,250
Now, if I may, Eric,
what was the algorithm

62
00:01:43,250 --> 00:01:45,020
via which you found us the number 50?

63
00:01:45,020 --> 00:01:46,050
AUDIENCE: Linear search.

64
00:01:46,050 --> 00:01:48,380
SPEAKER 1: OK, linear
search, meaning what to you?

65
00:01:48,380 --> 00:01:52,070
AUDIENCE: You just go in a line,
starting from there until there.

66
00:01:52,070 --> 00:01:54,200
SPEAKER 1: OK, that was a
very sophisticated answer

67
00:01:54,200 --> 00:01:55,650
to a term we've not yet introduced.

68
00:01:55,650 --> 00:01:59,150
And that's great, linear search
from left to right, so literally

69
00:01:59,150 --> 00:01:59,900
following a line.

70
00:01:59,900 --> 00:02:01,820
And was your algorithm
correct, would you say?

71
00:02:01,820 --> 00:02:02,460
AUDIENCE: Yes.

72
00:02:02,460 --> 00:02:03,870
SPEAKER 1: OK, so it was correct.

73
00:02:03,870 --> 00:02:05,900
But there's these different
parameters that we

74
00:02:05,900 --> 00:02:08,450
want to optimize solutions for
not just correctness, but what

75
00:02:08,450 --> 00:02:09,970
other property as well?

76
00:02:09,970 --> 00:02:10,730
AUDIENCE: Design.

77
00:02:10,730 --> 00:02:12,810
SPEAKER 1: So maybe design,
right, the efficiency.

78
00:02:12,810 --> 00:02:14,960
So was that the most
efficient you could have done?

79
00:02:14,960 --> 00:02:18,020
AUDIENCE: Actually, yeah, I think so.

80
00:02:18,020 --> 00:02:18,800
[LAUGHTER]

81
00:02:18,800 --> 00:02:19,800
SPEAKER 1: And why do you say that?

82
00:02:19,800 --> 00:02:21,810
AUDIENCE: Because-- so
the numbers are sorted.

83
00:02:21,810 --> 00:02:25,020
So at the end of the day, I have
to look through every single one.

84
00:02:25,020 --> 00:02:25,220
SPEAKER 1: Yeah.

85
00:02:25,220 --> 00:02:27,380
AUDIENCE: And it's just by
chance that the 50 was at last.

86
00:02:27,380 --> 00:02:28,170
SPEAKER 1: Exactly.

87
00:02:28,170 --> 00:02:30,230
So it's unfortunate that
they were all random.

88
00:02:30,230 --> 00:02:32,540
And I didn't want to tell you because I
didn't want to bias your algorithm one

89
00:02:32,540 --> 00:02:33,240
way or the other.

90
00:02:33,240 --> 00:02:36,260
But not knowing if they're sorted
and them not even being sorted

91
00:02:36,260 --> 00:02:39,820
means that that is the best you
can do, look at all of the doors

92
00:02:39,820 --> 00:02:41,120
to find the number in question.

93
00:02:41,120 --> 00:02:43,760
And maybe you could have gotten
lucky, if we had put 50 here.

94
00:02:43,760 --> 00:02:45,560
But in the worst case,
Eric was, of course,

95
00:02:45,560 --> 00:02:48,140
going to have to do exactly
that, searching all of the boxes.

96
00:02:48,140 --> 00:02:49,340
So thank you, Eric.

97
00:02:49,340 --> 00:02:50,960
Stay on stage with us, if
you would, for a moment.

98
00:02:50,960 --> 00:02:53,090
And a round of applause, if we
could, for finding 50 so well.

99
00:02:53,090 --> 00:02:53,590
[APPLAUSE]

100
00:02:53,590 --> 00:02:55,980
[? Nizari, ?] could you come on up?

101
00:02:55,980 --> 00:02:58,250
We need you not to look at
the numbers, because Brian

102
00:02:58,250 --> 00:02:59,690
needs to do a little bit of magic.

103
00:02:59,690 --> 00:03:02,030
And he's going to put some of
the numbers back into the locker.

104
00:03:02,030 --> 00:03:04,110
So literally everyone in
the room will know what's

105
00:03:04,110 --> 00:03:05,790
going on except you, at the moment.

106
00:03:05,790 --> 00:03:08,000
But we're going to give you
the added bonus this time

107
00:03:08,000 --> 00:03:10,940
of sorting the numbers in advance.

108
00:03:10,940 --> 00:03:13,420
So Brian is in the process of
sorting some numbers for us.

109
00:03:13,420 --> 00:03:15,260
The goal at hand, in
just a moment, is still

110
00:03:15,260 --> 00:03:17,240
going to be the find the number 50.

111
00:03:17,240 --> 00:03:20,640
I'm really just stalling right
now because he's still doing this.

112
00:03:20,640 --> 00:03:24,590
So I don't really have anything
interesting to say just yet.

113
00:03:24,590 --> 00:03:25,520
Brian's back now.

114
00:03:25,520 --> 00:03:26,320
Hold on.

115
00:03:26,320 --> 00:03:27,650
And would you like to
introduce yourself maybe?

116
00:03:27,650 --> 00:03:28,440
AUDIENCE: I'm [? Nizari. ?]

117
00:03:28,440 --> 00:03:29,450
SPEAKER 1: [? Nizari, ?]
and what year are you?

118
00:03:29,450 --> 00:03:31,470
AUDIENCE: I'm a high
school student, a senior.

119
00:03:31,470 --> 00:03:32,350
SPEAKER 1: Wonderful.

120
00:03:32,350 --> 00:03:32,990
At what school?

121
00:03:32,990 --> 00:03:34,160
AUDIENCE: Cambridge Rindge and
Latin, it's down the street.

122
00:03:34,160 --> 00:03:35,430
SPEAKER 1: Just down the road.

123
00:03:35,430 --> 00:03:36,890
So glad you can join us here today.

124
00:03:36,890 --> 00:03:38,630
And perfect timing, if I may.

125
00:03:38,630 --> 00:03:41,090
Now we have seven
lockers here behind you.

126
00:03:41,090 --> 00:03:43,130
And the goal now is to
still find the number 50.

127
00:03:43,130 --> 00:03:45,720
But I'm going to tell you
that the numbers are sorted.

128
00:03:45,720 --> 00:03:48,960
So what's going to be your
algorithm, if not the same as Eric?

129
00:03:48,960 --> 00:03:49,960
AUDIENCE: I will start--

130
00:03:49,960 --> 00:03:50,370
SPEAKER 1: And here you go.

131
00:03:50,370 --> 00:03:52,310
AUDIENCE: I'm going to
start in the middle.

132
00:03:52,310 --> 00:03:54,260
SPEAKER 1: All right, go ahead
and show us what's in the middle.

133
00:03:54,260 --> 00:03:55,660
AUDIENCE: Middle number is seven.

134
00:03:55,660 --> 00:03:56,540
SPEAKER 1: All right.

135
00:03:56,540 --> 00:03:58,550
And now what's your
next step going to be?

136
00:03:58,550 --> 00:03:59,930
AUDIENCE: So I want to get to 50.

137
00:03:59,930 --> 00:04:02,630
So assuming that they're sorted,
I'm going to go this way.

138
00:04:02,630 --> 00:04:03,560
SPEAKER 1: Go to the right, OK.

139
00:04:03,560 --> 00:04:05,970
So we have three lockers
remaining on the right-hand side.

140
00:04:05,970 --> 00:04:07,100
What's your instinct now?

141
00:04:07,100 --> 00:04:09,480
AUDIENCE: Mm, I'm going
to start with this locker.

142
00:04:09,480 --> 00:04:11,390
SPEAKER 1: OK, this one being
in the middle of those three.

143
00:04:11,390 --> 00:04:11,770
And you find?

144
00:04:11,770 --> 00:04:12,800
AUDIENCE: And we got 81.

145
00:04:12,800 --> 00:04:13,290
SPEAKER 1: 81.

146
00:04:13,290 --> 00:04:14,660
AUDIENCE: So I know that's too big.

147
00:04:14,660 --> 00:04:15,480
SPEAKER 1: Way too far.

148
00:04:15,480 --> 00:04:17,120
AUDIENCE: Hoo, so I'm
going to go with this one.

149
00:04:17,210 --> 00:04:18,830
SPEAKER 1: Which is now in
the middle of the two lockers.

150
00:04:18,830 --> 00:04:19,450
AUDIENCE: And I got 50.

151
00:04:19,450 --> 00:04:22,430
SPEAKER 1: And a round of applause,
if we could, for [? Nizari. ?]

152
00:04:22,430 --> 00:04:25,100
[APPLAUSE]

153
00:04:25,100 --> 00:04:27,050
Congratulations and
thank you to you both.

154
00:04:27,050 --> 00:04:28,200
So thanks to you both.