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#!/usr/bin/env gawk
# Challenge 119
#
# TASK #2 - Sequence without 1-on-1
# Submitted by: Cheok-Yin Fung
# Write a script to generate sequence starting at 1. Consider the increasing
# sequence of integers which contain only 1�s, 2�s and 3�s, and do not have any
# doublets of 1�s like below. Please accept a positive integer $N and print the
# $Nth term in the generated sequence.
#
# 1, 2, 3, 12, 13, 21, 22, 23, 31, 32, 33, 121, 122, 123, 131,
#
# Example
# Input: $N = 5
# Output: 13
#
# Input: $N = 10
# Output: 32
#
# Input: $N = 60
# Output: 2223
function next_seq() {
while (1) {
n++
if (match(n, "^[123]+$") && !match(n, "11")) {
return n;
}
}
}
BEGIN {
n = 0
num = ARGV[1]
for (i = 1; i <= num; i++)
n = next_seq();
print n
exit
}
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