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#include "aoc.h"
namespace aoc2016 {
size_t position_at(int t, int slot, size_t p) { return t > 0 ? (t % slot + p) % slot : p; }
struct disc {
int slots;
size_t p;
};
static bool same(size_t* ps, int x) {
for (int i = 0; i < x; i++) {
if (ps[i] != ps[x]) {
return false;
}
}
return true;
}
int first_catch(disc ds[7], int x) {
int t{0};
while (true) {
size_t ps[7] = {0, 0, 0, 0, 0, 0, 0};
for (size_t i = 0; i < 7; i++) {
ps[i] = position_at(t + i + 1, ds[i].slots, ds[i].p);
}
if (same(ps, x)) {
return t;
}
t++;
}
}
std::pair<int64_t, int64_t> day15(line_view) {
disc ds[7] = {{17, 1}, {7, 0}, {19, 2}, {5, 0}, {3, 0}, {13, 5}, {11, 0}};
return {first_catch(ds, 5), first_catch(ds, 6)};
}
} // namespace aoc2016
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