Advent of Code 2018 day 14

14.c

#include <stdio.h>
#include <stdlib.h>

static int *scores;
static size_t size;
static size_t capacity;
static int current;

void AddScore(int x) {
    if (size == capacity) {
        capacity = capacity == 0 ? 16 : 2*capacity;
        scores = realloc(scores, sizeof(int)*capacity);
    }
    scores[size++] = x;
    current = (10*current + x)%1000000;
}

void Solve(int target) {
    AddScore(3);
    AddScore(7);
    for (int i = 0, j = 1;;) {
        int x = scores[i] + scores[j];
        if (x < 10) {
            AddScore(x);
            if (current == target) break;
        } else {
            AddScore(x/10);
            if (current == target) break;
            AddScore(x - x/10*10);
            if (current == target) break;
        }
        i = (i + 1 + scores[i]);
        while (i >= size) i -= size;
        j = (j + 1 + scores[j]);
        while (j >= size) j -= size;
    }
}

int main() {
    int target = 0;
    if (scanf("%d", &target) != 1) {
        return 1;
    }
    Solve(target);
    printf("%d\n", size - 6);
    return 0;
}

Regel 27 / 29. Je weet dat de scores niet boven de 9 kunnen uitkomen, dus x/10 is altijd 1 en x/10*10 is altijd 10 als x>=10