Challenge 188

You are given list of integers @list of size \$n and divisor \$k.

Write a script to find out count of pairs in the given list that satisfies the following rules.

The pair (i, j) is eligible if and only if a) 0 <= i < j < len(list) b) list[i] + list[j] is divisible by k

```Example 1
Input: @list = (4, 5, 1, 6), \$k = 2
Output: 2

Example 2
Input: @list = (1, 2, 3, 4), \$k = 2
Output: 2

Example 3
Input: @list = (1, 3, 4, 5), \$k = 3
Output: 2

Example 4
Input: @list = (5, 1, 2, 3), \$k = 4
Output: 2

Example 5
Input: @list = (7, 2, 4, 5), \$k = 4
Output: 1
```

Raku

Go over all combinations of elements as per rules and check if their sum is divisible by divisor.

```unit sub MAIN(
Int \$divisor, *@list is copy where *.elems > 0
);
@list = @list>>.Int;

my Int \$pairs;
for 0 ... @list.end -> \$i {
for \$i ... @list.end -> \$j {
next if \$i == \$j;
\$pairs++ if (@list[\$i] + @list[\$j]) %% \$divisor;
}
}
put \$pairs;
```

Andinus / 2022-10-27 / Modified: 2022-10-27 Thu 14:30 Emacs 28.2 (Org mode 9.5.5)