# Challenge 130

## Table of Contents

## Task 1 - Odd Number

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

- Program: 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);