Josephus Problem in Awk

Welcome to the Josephus Problem in Awk page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

function usage() {
    print "Usage: please input the total number of people and number of people to skip."
    exit(1)
}

function str_to_number(s) {
    return (s ~ /^\s*[+-]*[0-9]+\s*$/) ? s + 0 : "ERROR"
}

# Reference: https://en.wikipedia.org/wiki/Josephus_problem#The_general_case
#
# Use zero-based index algorithm:
#
#     g(1, k) = 0
#     g(m, k) = [g(m - 1, k) + k] MOD m, for m = 2, 3, ..., n
#
# Final answer is g(n, k) + 1 to get back to one-based index
function josephus_problem(n, k,  g, m) {
    g = 0
    for (m = 2; m <= n; m++) {
        g = (g + k) % m
    }

    return g + 1
}

BEGIN {
    if (ARGC < 3) {
        usage()
    }

    n = str_to_number(ARGV[1])
    k = str_to_number(ARGV[2])
    if (n == "ERROR" || k == "ERROR") {
        usage()
    }

    print josephus_problem(n, k)
}

Josephus Problem in Awk was written by:

• rzuckerm

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.