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#include "aoc.h"
#include <math.h>
namespace aoc2017 {
std::pair<int, int> circle(int t) {
int i = 1;
int j = 0;
while ((i * i) < t) {
i += 2;
j += 1;
}
return {j, i};
}
void middles(int i, int m[]) {
int x = i * i;
for (int a : {0, 1, 2, 3}) {
int n = x - i + 1;
m[a] = (n + x) / 2;
x = n;
}
}
int closest(int t, int m[]) {
int min{INT32_MAX};
for (int a : {0, 1, 2, 3}) {
int d = std::abs(t - m[a]);
if (d < min) {
min = d;
}
}
return min;
}
int day3(int target) {
auto p = circle(target);
int ms[4] = {0};
middles(p.second, ms);
// printf("%d -> %d %d %d %d\n", target, ms[0], ms[1], ms[2], ms[3]);
int d = closest(target, ms);
return d + p.first;
}
int day3part2(int target) {
spiral_grid grid{9};
return grid.fill_until(target);
}
} // namespace aoc2017
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