From bfb20ad7efd883f8df62bca6540ecf1bc88fca0f Mon Sep 17 00:00:00 2001
From: Stephen Lynn <bizlsg@localhost.localdomain>
Date: Sun, 24 Dec 2023 12:33:01 +0800
Subject: faster ch-1: ch-1a.pl

---
 challenge-248/steve-g-lynn/perl/ch-1a.pl | 81 ++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100755 challenge-248/steve-g-lynn/perl/ch-1a.pl

diff --git a/challenge-248/steve-g-lynn/perl/ch-1a.pl b/challenge-248/steve-g-lynn/perl/ch-1a.pl
new file mode 100755
index 0000000000..3c5edede1f
--- /dev/null
+++ b/challenge-248/steve-g-lynn/perl/ch-1a.pl
@@ -0,0 +1,81 @@
+#!/usr/bin/env -S perl -wl
+
+#-- faster version that does everything in Inline Pdlpp
+
+use PDL;
+use Inline Pdlpp;
+
+local *shortest_distance_a=sub {
+    # faster version using PP for outer loop
+    my ($str,$chr)=@_;
+    ($str =~ /$chr/) || return 0;
+
+    (1==length($chr)) || (die "Single character input needed:$!\n");
+    
+    #-- get indices where the element equals chr
+    my $grp=pdl(grep {$chr eq substr($str,$_,1)} 0..length($str));
+    my $retval=$grp->shortest_distance_pp(length($str));
+    
+    return $retval;
+ };
+
+print &shortest_distance_a('loveleetcode','e');
+#[3 2 1 0 1 0 0 1 2 2 1 0]
+
+print &shortest_distance_a('aaab','b');
+#[3 2 1 0]
+
+__DATA__
+
+__Pdlpp__
+
+
+pp_def(
+    'shortest_distance_pp',
+    Pars => 'indx a(m); indx lenstr(); [o]b(n);',
+    RedoDimsCode => '$SIZE(n)=$lenstr();',
+    GenericTypes => ['N'], 
+    Code => q{
+        PDL_Indx i,j,size_m, size_n, ctr_stop;
+        size_m=$SIZE(m);
+        size_n=$SIZE(n);
+        ctr_stop=$a(m=>0);
+        if (0 < $a(m=>0)){
+            for (i=0; i < ctr_stop; i++) {
+                $b(n=>i)=ctr_stop-i;
+            } 
+        }
+        PDL_Indx a1,a2,c_mid,gap_size;
+        for (j=0; j<size_m; j++) {
+            a1=$a(m=>j);
+            a2=$a(m=>j+1);
+            gap_size=a2-a1+1;
+            
+            if (0==(gap_size % 2)){
+                c_mid=gap_size/2;
+                for (i=a1; i < a1+c_mid; i++) {
+                    $b(n=>i)=i-a1;             
+                }
+                for (i=a1+c_mid; i <= a2; i++) {
+                    $b(n=>i)=a2-i;
+                } 
+            }   
+            else {
+                c_mid=(gap_size+1)/2;
+                for (i=a1; i < a1+c_mid; i++) {
+                    $b(n=>i)=i-a1;             
+                }
+                for (i=a1+c_mid; i <= a2; i++) {
+                    $b(n=>i)=a2-i;
+                }         
+            }
+        }       
+        if (size_n > $a(m=>-1)+1){
+            a1=$a(m=>size_m-1);
+            for (i=a1; i < size_n; i++) {
+                $b(n=>i)=i-a1;
+            } 
+        }                        
+    },
+);
+
-- 
cgit