Merge pull request #9386 from bn-ssotka/ch-251-p2

CH-251 part 2, lucky numbers

1 files changed, 38 insertions, 0 deletions

diff --git a/challenge-251/bn-ssotka/raku/ch-2.raku b/challenge-251/bn-ssotka/raku/ch-2.raku
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+#!/usr/bin/env raku
+
+# You are given a m x n matrix of distinct numbers.
+
+# Write a script to return the lucky number, if there is one, or -1 if not.
+
+# A lucky number is an element of the matrix such that it is
+# the minimum element in its row and maximum in its column.
+
+sub get-lucky (@matrix) {
+    my @row_mins = @matrix.map: *.min; # get the mins of each row
+    my @rotated_matrix = [Z] @matrix;  # rotate the matrix
+    my @col_maxs = @rotated_matrix.map: *.max; # get the max of each of the rotated rows
+
+    my @lucky = @row_mins ∩ @col_maxs; # get the intersection of the two
+    return @lucky ?? @lucky[0] !! -1;
+}
+my @test-matricies = (
+    (
+        [ 3,  7,  8],
+        [ 9, 11, 13],
+        [15, 16, 17]
+    ),
+    (
+        [ 1, 10,  4,  2],
+        [ 9,  3,  8,  7],
+        [15, 16, 17, 12]
+    ),
+    (
+        [7 ,8],
+        [1 ,2]
+    )
+);
+
+for @test-matricies -> @matrix {
+    say @matrix;
+    say get-lucky(@matrix);
+}