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━━━━━━━━━━━━━━━
CHALLENGE 188
Andinus
━━━━━━━━━━━━━━━
2022-10-27
1 Task 1 - Divisible Pairs
══════════════════════════
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
└────
1.1 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;
└────
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