1
00:00:00,000 --> 00:00:07,900
[No Audio]

2
00:00:07,901 --> 00:00:10,200
Consider an office environment where there is

3
00:00:10,201 --> 00:00:13,333
a boss and he has two secretaries. He needs

4
00:00:13,334 --> 00:00:16,033
these services of the secretaries from time to time.

5
00:00:16,633 --> 00:00:18,700
The secretaries are also involved in

6
00:00:18,701 --> 00:00:21,300
other activities, and therefore has their own

7
00:00:21,301 --> 00:00:24,466
schedule of meetings. Some of the meetings of

8
00:00:24,467 --> 00:00:27,566
the secretaries may be overlapping. The boss

9
00:00:27,567 --> 00:00:30,433
wants to know the time slots in which both

10
00:00:30,434 --> 00:00:33,000
the secretaries may be busy, that is both

11
00:00:33,001 --> 00:00:36,166
have meetings. This will help him in finding

12
00:00:36,200 --> 00:00:38,700
out a time slot in which at least one of the

13
00:00:38,701 --> 00:00:41,633
secretary will be free, so that some tasks may

14
00:00:41,634 --> 00:00:45,100
be assigned to him. To accomplish this, we

15
00:00:45,101 --> 00:00:47,133
need to find the overlapping times of the

16
00:00:47,134 --> 00:00:50,700
secretaries. Let us start implementing this problem.

17
00:00:51,200 --> 00:00:52,566
We will assume that the meeting

18
00:00:52,567 --> 00:00:54,900
schedule for the two secretaries are given to

19
00:00:54,901 --> 00:00:57,966
us in the form of factors. Each meeting is

20
00:00:58,000 --> 00:01:00,533
associated with the start and end times, which

21
00:01:00,534 --> 00:01:02,800
is also given in the form of factors.

22
00:01:03,600 --> 00:01:06,300
Let us declare a couple of variables which will

23
00:01:06,301 --> 00:01:08,966
contain the meeting timings for the two employees.

24
00:01:08,967 --> 00:01:17,933
[No Audio]

25
00:01:17,966 --> 00:01:20,466
Each employee meeting schedules are given by

26
00:01:20,467 --> 00:01:22,733
vectors, and the entries in the vectors are

27
00:01:22,734 --> 00:01:24,666
showing the time slots in which the meeting

28
00:01:24,667 --> 00:01:27,433
will be held. The first value represents the

29
00:01:27,434 --> 00:01:29,633
starting time and the second value represents

30
00:01:29,634 --> 00:01:32,533
the ending time of the meeting. The times in

31
00:01:32,534 --> 00:01:35,933
this case are in 24 hours system. For

32
00:01:35,934 --> 00:01:38,433
example, the value 13 means 1pm in the

33
00:01:38,434 --> 00:01:41,100
afternoon, and the value 15 will mean 3pm in

34
00:01:41,101 --> 00:01:44,700
the afternoon. Please note that, to access the

35
00:01:44,701 --> 00:01:46,766
starting or ending time information for a

36
00:01:46,767 --> 00:01:49,500
specific meeting, we will use the syntax of

37
00:01:49,501 --> 00:01:51,100
couple of square brackets.

38
00:01:52,300 --> 00:01:53,500
The index value in

39
00:01:53,501 --> 00:01:55,366
the first square bracket will corresponds to

40
00:01:55,367 --> 00:01:57,700
the meeting number, and the index in the

41
00:01:57,701 --> 00:01:59,833
second square bracket will correspond to

42
00:02:00,200 --> 00:02:02,100
either the starting or ending times.

43
00:02:02,900 --> 00:02:05,266
Next, we will implement a function for determining the

44
00:02:05,267 --> 00:02:08,500
overlapping or intersecting meeting timings.

45
00:02:08,501 --> 00:02:14,766
[No Audio]

46
00:02:14,767 --> 00:02:16,700
The input to this function will be the

47
00:02:16,733 --> 00:02:18,933
vectors containing the meeting information of

48
00:02:18,934 --> 00:02:22,700
the two secretaries, which are of type vectors of vectors.

49
00:02:22,701 --> 00:02:24,800
[No Audio]

50
00:02:24,801 --> 00:02:26,100
The output will be the vector

51
00:02:26,101 --> 00:02:28,733
containing the overlapping timings, and will

52
00:02:28,734 --> 00:02:31,500
be of type vector of vectors.

53
00:02:31,501 --> 00:02:38,566
[No Audio]

54
00:02:38,567 --> 00:02:40,966
First, I will declare an empty variable which

55
00:02:40,967 --> 00:02:42,700
will contain the overlapping timings.

56
00:02:43,633 --> 00:02:45,666
I will return this variable, so therefore

57
00:02:45,667 --> 00:02:48,333
its type will also be that of vectors of vectors.

58
00:02:49,000 --> 00:02:50,900
I will also mention its name without

59
00:02:50,901 --> 00:02:52,866
a semicolon to tell Rust compiler,

60
00:02:52,867 --> 00:02:54,500
that it is a returning value.

61
00:02:54,501 --> 00:03:00,266
[No Audio]

62
00:03:00,267 --> 00:03:02,000
Next, we will iterate through all the

63
00:03:02,001 --> 00:03:05,566
meetings of a secretary a, and we'll check it

64
00:03:05,567 --> 00:03:08,400
with all the meetings of secretary b, one by

65
00:03:08,401 --> 00:03:12,033
one to see if they have an overlap. We will

66
00:03:12,034 --> 00:03:14,366
use a couple of loops for this purpose. The

67
00:03:14,367 --> 00:03:16,233
outer loop will be used to iterate through

68
00:03:16,234 --> 00:03:18,866
all the meetings of secretary a,

69
00:03:18,867 --> 00:03:20,700
and the inner loop will iterate through all

70
00:03:20,701 --> 00:03:22,500
the meetings of secretary b.

71
00:03:22,501 --> 00:03:28,500
[No Audio]

72
00:03:28,501 --> 00:03:30,300
The logic in the loop will work by

73
00:03:30,301 --> 00:03:32,700
considering the first meeting of secretary a,

74
00:03:32,701 --> 00:03:34,466
which will be checked with all the meetings

75
00:03:34,467 --> 00:03:37,433
of secretary b. Then the second meeting of

76
00:03:37,434 --> 00:03:39,533
secretary a will be checked with all the

77
00:03:39,534 --> 00:03:42,100
meetings of secretary b, and so on.

78
00:03:42,633 --> 00:03:45,466
The variable i will correspond to meetings of a,

79
00:03:45,533 --> 00:03:48,600
and the variable j will correspond to meeting of b.

80
00:03:49,133 --> 00:03:52,300
To check the overlap of meetings, we

81
00:03:52,301 --> 00:03:54,066
will first compute the starting and ending

82
00:03:54,067 --> 00:03:55,466
times of the meetings.

83
00:03:55,467 --> 00:04:02,833
[No Audio]

84
00:04:02,834 --> 00:04:04,533
The first level of square brackets

85
00:04:04,534 --> 00:04:06,266
corresponds to the meeting number, and the

86
00:04:06,267 --> 00:04:08,433
second level of index is used to reflect the

87
00:04:08,434 --> 00:04:12,166
starting or ending time. For the secretary a

88
00:04:12,167 --> 00:04:16,300
we use, the index of outer, the  index of outer for loop

89
00:04:16,301 --> 00:04:19,033
which is i, and then the index 0

90
00:04:19,034 --> 00:04:21,166
which corresponds to the starting time, and

91
00:04:21,167 --> 00:04:23,547
for the secretary b we use the index of j,

92
00:04:23,548 --> 00:04:25,500
which corresponds to the inner for loop.

93
00:04:26,200 --> 00:04:28,300
In the same way, we will also capture the ending

94
00:04:28,301 --> 00:04:30,533
times for the meetings of the two secretaries.

95
00:04:30,534 --> 00:04:36,000
[No Audio]

96
00:04:36,001 --> 00:04:38,100
When this code executes, the first meeting of

97
00:04:38,101 --> 00:04:40,133
secretary a will be checked with all the

98
00:04:40,134 --> 00:04:42,266
meetings of the secretary b, and then the

99
00:04:42,267 --> 00:04:44,666
second meeting of secretary a will be

100
00:04:44,700 --> 00:04:46,733
checked against all the meetings of secretary

101
00:04:46,734 --> 00:04:50,133
b, and so on. Next we will determine if the

102
00:04:50,134 --> 00:04:52,500
two meetings has an overlap or not. I will

103
00:04:52,501 --> 00:04:55,533
declare another function for this purpose called overlap.

104
00:04:55,534 --> 00:05:00,766
[No Audio]

105
00:05:00,767 --> 00:05:03,300
This function will have four input

106
00:05:03,301 --> 00:05:05,666
values of type i32, which represents the

107
00:05:05,667 --> 00:05:07,833
starting and ending times of the meetings of

108
00:05:07,834 --> 00:05:11,100
the two secretaries. The output will be an

109
00:05:11,101 --> 00:05:13,233
optionVector containing the overlapping

110
00:05:13,234 --> 00:05:17,000
time information. First, I will declare a

111
00:05:17,001 --> 00:05:19,400
variable intersection_time, which

112
00:05:19,401 --> 00:05:21,766
will contain the intersection times if any,

113
00:05:21,866 --> 00:05:24,500
and I will initialize it as an empty vector.

114
00:05:24,501 --> 00:05:29,100
[No Audio]

115
00:05:29,101 --> 00:05:31,100
Next, we need to define the conditions for

116
00:05:31,101 --> 00:05:33,366
the overlap. In this case, we have two

117
00:05:33,367 --> 00:05:35,966
intervals of values, and we need to determine

118
00:05:35,967 --> 00:05:39,133
if the interval has an overlap. Let us now

119
00:05:39,134 --> 00:05:41,533
learn how we can determine the overlap

120
00:05:41,534 --> 00:05:43,500
between intervals using some visuals.

121
00:05:43,501 --> 00:05:46,500
[No Audio]

122
00:05:46,501 --> 00:05:48,466
The rectangles represents the meetings and the

123
00:05:48,467 --> 00:05:50,600
values inside it are the starting and ending

124
00:05:50,601 --> 00:05:54,600
times of the meeting. We have at least three

125
00:05:54,601 --> 00:05:56,966
possible cases. In the first case, we do not

126
00:05:56,967 --> 00:05:59,166
have an overlap. In the second case, we have

127
00:05:59,167 --> 00:06:02,000
an overlap of one hour. In the third case,

128
00:06:02,033 --> 00:06:04,300
again, we have an overlap of one hour, but

129
00:06:04,301 --> 00:06:06,000
with a difference that the meeting of b

130
00:06:06,001 --> 00:06:08,300
starts first followed by the meeting of a.

131
00:06:10,100 --> 00:06:12,800
The essential condition for the two meetings

132
00:06:12,801 --> 00:06:14,933
to have an overlap is that, one of the meeting

133
00:06:14,934 --> 00:06:17,433
should not end before the start of the other.

134
00:06:17,500 --> 00:06:19,600
This condition may be checked by checking

135
00:06:19,601 --> 00:06:21,666
that the maximum of the starting times of the

136
00:06:21,667 --> 00:06:23,833
two meetings is less than the minimum of the

137
00:06:23,834 --> 00:06:25,766
ending times of the two meetings,

138
00:06:25,966 --> 00:06:28,300
let us look into this condition.

139
00:06:28,301 --> 00:06:31,466
[No Audio]

140
00:06:31,467 --> 00:06:32,466
In the first case, the

141
00:06:32,467 --> 00:06:34,700
maximum of the two starting times that is

142
00:06:34,701 --> 00:06:37,300
7 and 10 is the value 10. However, the

143
00:06:37,301 --> 00:06:40,200
minimum of the ending times, that is 9 and 12 is 9.

144
00:06:40,900 --> 00:06:42,933
Since 10 is not less than 9,

145
00:06:42,934 --> 00:06:45,633
therefore, the two meetings does not have an

146
00:06:45,634 --> 00:06:48,700
overlap. However, in case of 2 and 3,

147
00:06:48,733 --> 00:06:50,833
there is an overlap, because this condition is

148
00:06:50,834 --> 00:06:53,333
being true for them. For instance, in case 2,

149
00:06:53,600 --> 00:06:56,400
the maximum of the starting times is 9, and

150
00:06:56,401 --> 00:06:58,766
the minimum of the ending times is 10. Since

151
00:06:58,767 --> 00:07:00,900
9 is less than 10, therefore, they will

152
00:07:00,901 --> 00:07:04,233
have an overlap. The lower end of the overlap

153
00:07:04,234 --> 00:07:06,633
interval will be given by the maximum of the

154
00:07:06,634 --> 00:07:09,533
starting times, and the lower end of the

155
00:07:09,534 --> 00:07:12,033
interval will be the minimum of the ending times.

156
00:07:12,200 --> 00:07:15,000
Let us code this now. I will first

157
00:07:15,001 --> 00:07:17,366
write a condition for comparing the maximum

158
00:07:17,367 --> 00:07:19,100
of the starting values with that of the

159
00:07:19,101 --> 00:07:21,833
minimum of the ending values. I will use the

160
00:07:21,834 --> 00:07:23,600
max and min functions from the standard

161
00:07:23,601 --> 00:07:26,333
library, so I will first include that and

162
00:07:26,334 --> 00:07:28,433
then I will write the conditions.

163
00:07:28,434 --> 00:07:34,333
[No Audio]

164
00:07:34,334 --> 00:07:36,300
If the condition is true, then I will store

165
00:07:36,301 --> 00:07:39,433
the lower and ending and of the interval in

166
00:07:39,434 --> 00:07:43,000
the intersection_time. First I will push the lower end,

167
00:07:43,001 --> 00:07:46,333
[No Audio]

168
00:07:46,334 --> 00:07:48,566
and then the upper end of the interval.

169
00:07:48,567 --> 00:07:54,233
[No Audio]

170
00:07:54,234 --> 00:07:57,000
In case there is no overlap, so I will return the None.

171
00:07:57,001 --> 00:08:00,100
[No Audio]

172
00:08:00,101 --> 00:08:01,733
Let us now use this function in the

173
00:08:01,734 --> 00:08:03,900
overlapping_meeting function.

174
00:08:05,100 --> 00:08:08,133
I will declare a variable overlap_status,

175
00:08:08,233 --> 00:08:10,700
and we'll assign to it the returning

176
00:08:10,701 --> 00:08:12,700
value from the function of overlap.

177
00:08:12,701 --> 00:08:19,100
[No Audio]

178
00:08:19,101 --> 00:08:22,933
I will next check if we have some overlap or not.

179
00:08:22,934 --> 00:08:27,000
[No Audio]

180
00:08:27,001 --> 00:08:28,500
If we have an overlap, then I

181
00:08:28,501 --> 00:08:30,333
will add the overlapping interval to the

182
00:08:30,334 --> 00:08:31,900
intersection vector.

183
00:08:31,901 --> 00:08:35,832
[No Audio]

184
00:08:35,833 --> 00:08:37,265
I need to wrap the value,

185
00:08:37,266 --> 00:08:39,799
because it is wrapped inside the Some variant

186
00:08:39,800 --> 00:08:41,100
of the option enum.

187
00:08:42,633 --> 00:08:43,732
Finally, we will call the

188
00:08:43,733 --> 00:08:45,700
overlapping_meetings function in

189
00:08:45,701 --> 00:08:47,500
the main with the vectors containing the

190
00:08:47,501 --> 00:08:49,833
meetings information for the two secretaries,

191
00:08:50,033 --> 00:08:52,333
and will assign its result to a variable.

192
00:08:52,334 --> 00:08:58,700
[No Audio]

193
00:08:58,701 --> 00:09:00,600
I will add a print statement to display

194
00:09:00,601 --> 00:09:02,400
the slots which has an overlap.

195
00:09:02,401 --> 00:09:06,500
[No Audio]

196
00:09:06,501 --> 00:09:07,900
Let us cargo run.

197
00:09:07,901 --> 00:09:11,000
[No Audio]

198
00:09:11,001 --> 00:09:13,333
We have two slots of overlapping timings.

199
00:09:13,633 --> 00:09:15,666
If we look at the first meeting of

200
00:09:15,667 --> 00:09:18,533
secretary a, then indeed it has an overlap

201
00:09:18,534 --> 00:09:22,600
with the first meeting of secretary b from 14 till 15.

202
00:09:23,000 --> 00:09:24,800
In the same way, the last meeting of

203
00:09:24,801 --> 00:09:27,300
secretary a, and the second meeting of

204
00:09:27,301 --> 00:09:30,933
secretary b, also has an overlap from 7 to 9.

205
00:09:32,300 --> 00:09:34,233
This overlapping information can now be

206
00:09:34,234 --> 00:09:36,433
used by the boss to determine the time slots

207
00:09:36,434 --> 00:09:39,366
in which at least one of his secretary may be free.

208
00:09:39,866 --> 00:09:41,866
That is it for this particular segment,

209
00:09:41,900 --> 00:09:44,133
we have looked at an example, and while

210
00:09:44,134 --> 00:09:46,433
solving and implementing the example we were

211
00:09:46,434 --> 00:09:48,633
able to practice multi-dimensional vectors

212
00:09:48,634 --> 00:09:51,600
and nested loops. In the next example, we

213
00:09:51,601 --> 00:09:53,633
will be learning the use of HashSet by

214
00:09:53,634 --> 00:09:56,266
implementing another real life problem. Do

215
00:09:56,267 --> 00:09:58,300
come back for that and until next tutorial,

216
00:09:58,333 --> 00:09:59,933
happy Rust programming.

217
00:09:59,934 --> 00:10:04,700
[No Audio]