Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>It seems like we could check for duplicates by multiplying all the numbers n...n+m together, and then comparing that value to the expected product of a sequence with no duplicates <strong>m!/(n-1)!</strong> (note that this assumes it is impossible for a sequence to pass both the expected sum test <strong>and</strong> the expected product test).</p> <p>So adding to <a href="https://stackoverflow.com/revisions/viewmarkup/224981">hazzen's pseudo-code</a>, we have:</p> <pre><code>is_range(int[] nums, int n, int m) { sum_to_m := (m * (m + 1)) / 2 expected_sum := sum_to_m - (n * (n - 1)) / 2 real_sum := sum(nums) expected_product := m! / (n - 1)! real_product := product(nums) return ((real_sum == expected_sum) &amp;&amp; (expected_product == real_product)) </code></pre> <p><br/> <strong>EDIT:</strong> Here's my solution in Java using the Sum of Squares to check for duplicates. It also handles any range (including negative numbers) by shifting the sequence to start at 1.</p> <pre><code>// low must be less than high public boolean isSequence(int[] nums, int low, int high) { int shift = 1 - low; low += shift; high += shift; int sum = 0; int sumSquares = 0; for (int i = 0; i &lt; nums.length; i++) { int num = nums[i] + shift; if (num &lt; low) return false; else if (num &gt; high) return false; sum += num; sumSquares += num * num; } int expectedSum = (high * (high + 1)) / 2; if (sum != expectedSum) return false; int expectedSumSquares = high * (high + 1) * (2 * high + 1) / 6; if (sumSquares != expectedSumSquares) return false; return true; } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POAlgorithm to determine if array contains n...n+m?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USDavid Crow
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTDownMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTDownMod
    1. CO[2,2,4,6,6] => ? ( assuming you know m and not n )
      singulars
      1. PO
      1. USKent Fredric
    2. COYou could do an initial pass to determine the n and subtract every element by that. The question is whether or not a sequence can be constructed to pass both the sum and product tests, which I don't know. But this is the most promising lead we have.
      singulars
      1. PO
      1. USKyle Cronin
    3. COThe expected product does not scale very well unless you allow infinite precision numbers; if you do, you are essentially using more than O(N) space to represent those numbers. That does give me the idea of trying something like summing n^2 to m^2 (which has a known formula). Not sure of props on it
      singulars
      1. PO
      1. UShazzen
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload