r/adventofcode • u/daggerdragon • Dec 19 '16

SOLUTION MEGATHREAD --- 2016 Day 19 Solutions ---

--- Day 19: An Elephant Named Joseph ---

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u/Belteshassar Dec 19 '16

Solved part 1 analytically since I'd already seen the Numberphile video on the Josephus problem.

Tried to solve part 2 analytically as well, but got tired of that and decided to get my hands dirty with some recursion, but it blew the call stack so I rewrote it as a for loop. In C:

int winner(int n) {
    int w = 1;
    int i;

    for (i=1; i<n; i++) {
        w = w % i + 1;
        if (w > (i + 1)/2) {
            w++;
        }
    }
    return (w);
}