AWK, C, Perl solutions for week 119, part 2.

3 files changed, 138 insertions, 0 deletions

diff --git a/challenge-119/abigail/awk/ch-2.awk b/challenge-119/abigail/awk/ch-2.awk
new file mode 100644
index 0000000000..c0f502e082
--- /dev/null
+++ b/challenge-119/abigail/awk/ch-2.awk
@@ -0,0 +1,43 @@
+#!/usr/bin/awk
+
+#
+# See ../README.md
+#
+
+#
+# Run as: awk -f ch-2.awk < input-file
+#
+
+function next_num (prev_num, tail) {
+    match (prev_num, /3*$/)
+    tail = substr (prev_num, RSTART)
+    gsub (/3/, 1, tail)
+    if (RLENGTH == length (prev_num)) {
+        prev_num = 1 tail
+    }
+    else {
+        prev_num = substr (prev_num, 1, RSTART - 2)      \
+                  (substr (prev_num, RSTART - 1, 1) + 1) \
+                   tail
+    }
+
+    #
+    # Replace the trailing 1s with 1212...
+    #
+    if (match (prev_num, /1+$/)) {
+        tail = substr (prev_num, RSTART)
+        gsub (/11/, "12", tail)
+        prev_num = substr (prev_num, 1, RSTART - 1) tail
+    }
+
+    return prev_num
+}
+                   
+
+{
+    n = 0
+    for (i = 0; i < $1; i ++) {
+        n = next_num(n)
+    }
+    print (n)
+}
diff --git a/challenge-119/abigail/c/ch-2.c b/challenge-119/abigail/c/ch-2.c
new file mode 100644
index 0000000000..45effb48c5
--- /dev/null
+++ b/challenge-119/abigail/c/ch-2.c
@@ -0,0 +1,56 @@
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-2.o ch-2.c; ./ch-2.o < input-file
+ */
+# define BUF_SIZE 32
+int main (void) {
+    int num;
+    char number [BUF_SIZE + 1];
+
+    number [BUF_SIZE] = '\0';
+
+    while (scanf ("%d", &num) == 1) {
+        /*
+         * Set the string to all 0s
+         */
+        for (int i = 0; i < BUF_SIZE; i ++) {
+            number [i] = '0';
+        }
+        while (num --) {
+            int i;
+            /*
+             * All trailing 3s will be turned into 1s
+             */
+            for (i = BUF_SIZE - 1; i > 0 && number [i] == '3'; i --) {
+                number [i] = '1';
+            }
+            /*
+             * Increment the digit before the trailing 3s
+             */
+            number [i] ++;
+            /*
+             * Replace every second 1 into a 2 of the trailing 1s
+             */
+            for (i = BUF_SIZE - 1; i > 0 && number [i] == '1'; i --);
+            i += 2;
+            for (;i < BUF_SIZE; i += 2) {
+                number [i] = '2';
+            }
+        }
+        /*
+         * Print the number, without the leading 0s
+         */
+        int i;
+        for (i = 0; i < BUF_SIZE && number [i] == '0'; i ++);
+        printf ("%s\n", number + i);
+    }
+
+    return (0);
+}
diff --git a/challenge-119/abigail/perl/ch-2.pl b/challenge-119/abigail/perl/ch-2.pl
new file mode 100644
index 0000000000..b53a827411
--- /dev/null
+++ b/challenge-119/abigail/perl/ch-2.pl
@@ -0,0 +1,39 @@
+#!/opt/perl/bin/perl
+
+use 5.032;
+
+use strict;
+use warnings;
+no  warnings 'syntax';
+
+use experimental 'signatures';
+use experimental 'lexical_subs';
+
+#
+# See ../README.md
+#
+
+#
+# Run as: perl ch-2.pl < input-file
+#
+
+sub next_num ($prev_num) {
+    #
+    # First, replace any trailing 3's with 1's, incrementing the
+    # digit which comes before.
+    # Then replace any trailing sequence of 1s with 12121... of the same
+    # length.
+    # Note we prepend the incoming number with "00" so we can anchor
+    # against it; we remove any leading 0s at the end.
+    #
+    "00$prev_num"                                                      =~
+       s!([012])(3*)$!($1 + 1) . (1 x length $2)!re                    =~
+       s!([023])((?:11)+)(1?)$!$1  . (12 x ((length $2) / 2)) . $3!re  =~
+       s!^0+!!r;
+}
+
+while (<>) {
+    my $n = 0;
+    $n = next_num $n for 1 .. $_;
+    say $n;
+}