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                             CHALLENGE 130

                                Andinus
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                               2021-09-14


Table of Contents
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Task 1 - Odd Number





Task 1 - Odd Number
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  You are given an array of positive integers, such that all the numbers
  appear even number of times except one number.

  Write a script to find that integer.

  Examples:
  ┌────
  │ Input: @N = (2, 5, 4, 4, 5, 5, 2)
  │ Output: 5 as it appears 3 times in the array where as all other numbers 2 and 4 appears exactly twice.
  │
  │ Input: @N = (1, 2, 3, 4, 3, 2, 1, 4, 4)
  │ Output: 4
  └────


Raku
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  • Program: <file:raku/ch-1.raku>

  `@nums' holds the input and `%seen' is True if it's seen odd number of
  times. We loop over `@nums' and invert the value of that number in
  `%seen'.

  ┌────
  │ my Bool %seen;
  │ %seen{$_} = !%seen{$_} for @nums;
  │ put %seen.grep(*.value).map(*.key);
  └────