Solutions for Challenge-345 (Perl)

3 files changed, 105 insertions, 0 deletions

diff --git a/challenge-345/vinod-k/blog.txt b/challenge-345/vinod-k/blog.txt
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+https://dev.to/vinodk89/perl-weekly-challenge-345-2bld
diff --git a/challenge-345/vinod-k/perl/ch-1.pl b/challenge-345/vinod-k/perl/ch-1.pl
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+++ b/challenge-345/vinod-k/perl/ch-1.pl
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+#!/usr/bin/perl
+
+###################################################################################
+#You are given an array of integers, @ints.
+#
+#Find all the peaks in the array, a peak is an element that is strictly greater 
+#than its left and right neighbours. Return the indices of all such peak positions.
+###################################################################################
+
+use strict;
+use warnings;
+
+sub find_peaks {
+    my @ints = @_;
+    my @peaks;
+    for my $i (0..$#ints) {
+        my $left  = ($i == 0 ) ? -1 : $ints[$i-1];
+        my $right = ($i == $#ints) ? -1 : $ints[$i+1];
+        if ($ints[$i] > $left && $ints[$i] > $right) {
+            push @peaks, $i;
+        }
+    }
+    return @peaks;
+}
+
+# Examples
+my @examples = (
+    [1, 3, 2],
+    [2, 4, 6, 5, 3],
+    [1, 2, 3, 2, 4, 1],
+    [5, 3, 1],
+    [1, 5, 1, 5, 1, 5, 1],
+);
+
+foreach my $ex (@examples) {
+    my @peaks = find_peaks(@$ex);
+    print "Input: (@$ex)\n";
+    print "Output: (", join(", ", @peaks), ")\n\n";
+}
diff --git a/challenge-345/vinod-k/perl/ch-2.pl b/challenge-345/vinod-k/perl/ch-2.pl
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+#!/usr/bin/perl
+use strict;
+use warnings;
+
+###################################################################################
+#You are given an integer array @ints where each element is either a positive 
+#integer or -1.
+#
+#We process the array from left to right while maintaining two lists:
+#
+#@seen: stores previously seen positive integers (newest at the front)
+#@ans: stores the answers for each -1
+#Rules:
+#
+#If $ints[i] is a positive number -> insert it at the front of @seen
+#If $ints[i] is -1:
+#Let $x be how many -1s in a row we’ve seen before this one.
+#
+#If $x < len(@seen) -> append seen[x] to @ans
+#
+#Else -> append -1 to @ans
+#
+#At the end, return @ans.
+###################################################################################
+
+sub process_ints {
+    my @ints = @_;
+    my @seen;
+    my @ans;
+    my $run = 0;
+
+    for (my $i = 0; $i < @ints; $i++) {
+        if ($ints[$i] == -1) {
+            my $x = 0;
+            my $j = $i - 1;
+            while ($j >= 0 && $ints[$j] == -1) {
+                $x++;
+                $j--;
+            }
+            if ($x < @seen) {
+                push @ans, $seen[$x];
+            } else {
+                push @ans, -1;
+            }
+        } else {
+            unshift @seen, $ints[$i];
+        }
+    }
+    return @ans;
+}
+
+# Example
+my @examples = (
+    [5, -1, -1],            # Output: (5, -1)
+    [3, 7, -1, -1, -1],     # Output: (7, 3, -1)
+    [2, -1, 4, -1, -1],     # Output: (2, 4, 2)
+    [10, 20, -1, 30, -1, -1], # Output: (20, 30, 20)
+    [-1, -1, 5, -1],        # Output: (-1, -1, 5)
+);
+
+foreach my $ex (@examples) {
+    my @ans = process_ints(@$ex);
+    print "Input: (@$ex)\n";
+    print "Output: (", join(", ", @ans), ")\n\n";
+}