AWK, C, Lua, Node.js and Perl solutions for week 119, part 2.

1 files changed, 51 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..351c34a6b7
--- /dev/null
+++ b/challenge-119/abigail/awk/ch-2.awk
@@ -0,0 +1,51 @@
+#!/usr/bin/awk
+
+#
+# See ../README.md
+#
+
+#
+# Run as: awk -f ch-2.awk < input-file
+#
+
+function next_num (prev_num, tail) {
+    #
+    # Find the trailing 3s
+    #
+    match (prev_num, /3*$/)
+    tail = substr (prev_num, RSTART)
+
+    #
+    # Replace them with 3s
+    #
+    gsub (/3/, 1, tail)
+
+    #
+    # Put the tail back in, incrementing the number before it.
+    # If we matched the full number, add a 1
+    #
+    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...
+    #
+    gsub (/11/, "12", prev_num)
+
+    return prev_num
+}
+                   
+
+{
+    n = 0
+    for (i = 0; i < $1; i ++) {
+        n = next_num(n)
+    }
+    print (n)
+}