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POHow can I find most frequent combinations of numbers in a list?
 

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  1. POHow can I find most frequent combinations of numbers in a list?
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    <p>Imagine you have a list of numbers (or letters), such as </p> <blockquote> <p>1177783777297461145777267337774652113777236237118777</p> </blockquote> <p>I want to find the most frequent combinations of numbers in this list:</p> <p>for 1-digit-long combinations - it is the most frequent number in this list</p> <p>for 2-digit-long combinations - probably '11'</p> <p>for 3-digits-long combinations - probably '777' etc</p> <p>Is there some special algorythm for such a tasks?</p> <p>UPDATE Well, by myself I have coded the following (Java). Looks like execution time is proportional to data size multiplied by pattern size:</p> <pre><code>public static void main(String[] args) { int DATA_SIZE = 10000; int[] data = new int[DATA_SIZE]; for (int i = 0; i &lt; DATA_SIZE; i++) { data[i] = (int) (10 * Math.random()) % 10; System.out.print(data[i]); } int[] pattern1 = new int[]{1, 2, 3}; int[] pattern2 = new int[]{7, 7, 7}; int[] pattern3 = new int[]{7, 7}; System.out.println(); System.out.println(match(data, pattern1)); System.out.println(match(data, pattern2)); System.out.println(match(data, pattern3)); } static int match(int[] data, int[] pattern) { int matches = 0; int i = 0; while (i &lt; data.length) { matches = isEqual(data, i, pattern) ? matches + 1 : matches; i++; } return matches; } static boolean isEqual(int[] a, int startIndex, int[] a2) { if (a == a2) { return true; } if (a == null || a2 == null) { return false; } for (int i = 0; i &lt; a2.length; i++) { if (a[startIndex + i] != a2[i]) { return false; } } return true; } </code></pre>
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      1. POHow can I find most frequent combinations of numbers in a list?
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      1. USMengdong Yang
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    1. COdid you even try solving it by yourself before posting on SO?
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    2. COPlease show your attempt.
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      1. POHow can I find most frequent combinations of numbers in a list?
      1. USAbhishek Bansal
    3. COGuys, yes I know the simplest way - just iterating through the array and storing the most frequent combinations in some map with pattern as a key, and counter as a value, but probably there are better approaches; as far as I understand this is a kind of a typical data mining task
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