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69 lines
3.3 KiB
HTML
69 lines
3.3 KiB
HTML
<p>Table: <code>Activity</code></p>
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<pre>
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+----------------+---------+
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| Column Name | Type |
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+----------------+---------+
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| machine_id | int |
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| process_id | int |
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| activity_type | enum |
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| timestamp | float |
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+----------------+---------+
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The table shows the user activities for a factory website.
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(machine_id, process_id, activity_type) is the primary key (combination of columns with unique values) of this table.
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machine_id is the ID of a machine.
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process_id is the ID of a process running on the machine with ID machine_id.
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activity_type is an ENUM (category) of type ('start', 'end').
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timestamp is a float representing the current time in seconds.
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'start' means the machine starts the process at the given timestamp and 'end' means the machine ends the process at the given timestamp.
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The 'start' timestamp will always be before the 'end' timestamp for every (machine_id, process_id) pair.</pre>
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<p> </p>
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<p>There is a factory website that has several machines each running the <strong>same number of processes</strong>. Write a solution to find the <strong>average time</strong> each machine takes to complete a process.</p>
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<p>The time to complete a process is the <code>'end' timestamp</code> minus the <code>'start' timestamp</code>. The average time is calculated by the total time to complete every process on the machine divided by the number of processes that were run.</p>
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<p>The resulting table should have the <code>machine_id</code> along with the <strong>average time</strong> as <code>processing_time</code>, which should be <strong>rounded to 3 decimal places</strong>.</p>
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<p>Return the result table in <strong>any order</strong>.</p>
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<p>The result format is in the following example.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong>
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Activity table:
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+------------+------------+---------------+-----------+
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| machine_id | process_id | activity_type | timestamp |
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+------------+------------+---------------+-----------+
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| 0 | 0 | start | 0.712 |
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| 0 | 0 | end | 1.520 |
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| 0 | 1 | start | 3.140 |
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| 0 | 1 | end | 4.120 |
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| 1 | 0 | start | 0.550 |
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| 1 | 0 | end | 1.550 |
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| 1 | 1 | start | 0.430 |
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| 1 | 1 | end | 1.420 |
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| 2 | 0 | start | 4.100 |
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| 2 | 0 | end | 4.512 |
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| 2 | 1 | start | 2.500 |
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| 2 | 1 | end | 5.000 |
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+------------+------------+---------------+-----------+
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<strong>Output:</strong>
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+------------+-----------------+
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| machine_id | processing_time |
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+------------+-----------------+
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| 0 | 0.894 |
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| 1 | 0.995 |
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| 2 | 1.456 |
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+------------+-----------------+
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<strong>Explanation:</strong>
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There are 3 machines running 2 processes each.
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Machine 0's average time is ((1.520 - 0.712) + (4.120 - 3.140)) / 2 = 0.894
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Machine 1's average time is ((1.550 - 0.550) + (1.420 - 0.430)) / 2 = 0.995
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Machine 2's average time is ((4.512 - 4.100) + (5.000 - 2.500)) / 2 = 1.456
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</pre>
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