258 lines
6.2 KiB
C
258 lines
6.2 KiB
C
#include "lib.h"
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#define DBG 0
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static
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alignas(0x40) unsigned char input[] = {
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#embed "day2_input.txt"
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};
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struct id {
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size_t len;
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bcdint v;
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};
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static
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bcdint next_palindrome_len2(bcdint in) {
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bcdint low = in & 0xF;
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bcdint high = in >> 4;
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bcdint higher = high + 1;
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bcdint high_pd = 0x11 * high;
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bcdint higher_pd = 0x11 * higher;
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return low > high ? higher_pd : high_pd;
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}
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static
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bcdint next_palindrome_len3(bcdint in) {
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bcdint nib0 = in & 0xF;
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bcdint nib1 = (in >> 4) & 0xF;
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bcdint high = in >> 8;
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bcdint higher = high + 1;
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bcdint high_pd = 0x111 * high;
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bcdint higher_pd = 0x111 * higher;
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if (nib1 < high) return high_pd;
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return nib0 > high ? higher_pd : high_pd;
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}
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static
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bcdint next_palindrome_len4(bcdint in) {
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bcdint nib0 = in & 0xF;
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bcdint nib1 = (in >> 4) & 0xF;
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bcdint nib2 = (in >> 8) & 0xF;
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bcdint nib3 = in >> 12;
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bcdint nib3er = nib3 + 1;
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bcdint nib3_pd = 0x1111 * nib3;
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bcdint nib3er_pd = 0x1111 * nib3er;
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bcdint nib10 = in & 0xFF;
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bcdint nib32 = in >> 8;
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bcdint nib32er = bcdadd(nib32, 1);
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bcdint nib32_pd = 0x0101 * nib32;
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bcdint nib32er_pd = 0x0101 * nib32er;
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bcdint r = nib3er_pd;
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if (nib3_pd > in) r = nib3_pd;
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if (nib32er_pd > in) r = nib32er_pd;
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if (nib32_pd > in) r = nib32_pd;
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return r;
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}
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static
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bcdint next_palindrome_len6(bcdint in) {
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bcdint nib0 = in & 0xF;
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bcdint nib1 = (in >> 4) & 0xF;
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bcdint nib2 = (in >> 8) & 0xF;
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bcdint nib3 = (in >> 12) & 0xF;
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bcdint nib4 = (in >> 16) & 0xF;
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bcdint nib5 = in >> 20;
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bcdint nib5er = nib5 + 1;
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bcdint nib5_pd = 0x111111 * nib5;
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bcdint nib5er_pd = 0x111111 * nib5er;
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bcdint nib10 = in & 0xFF;
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bcdint nib32 = (in >> 8) & 0xFF;
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bcdint nib54 = in >> 16;
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bcdint nib54er = bcdadd(nib54, 1);
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bcdint nib54_pd = 0x010101 * nib54;
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bcdint nib54er_pd = 0x010101 * nib54er;
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bcdint nib210 = in & 0xFFF;
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bcdint nib543 = in >> 12;
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bcdint nib543er = bcdadd(nib543, 1);
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bcdint nib543_pd = 0x001001 * nib543;
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bcdint nib543er_pd = 0x001001 * nib543er;
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bcdint r = nib5er_pd;
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if (nib5_pd > in) r = MIN(r,nib5_pd);
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if (nib54er_pd > in) r = MIN(r,nib54er_pd);
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if (nib54_pd > in) r = MIN(r,nib54_pd);
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if (nib543er_pd > in) r = MIN(r,nib543er_pd);
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if (nib543_pd > in) r = MIN(r,nib543_pd);
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return r;
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}
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static
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bcdint next_palindrome_len8(bcdint in) {
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bcdint nib0 = in & 0xF;
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bcdint nib1 = (in >> 4) & 0xF;
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bcdint nib2 = (in >> 8) & 0xF;
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bcdint nib3 = (in >> 12) & 0xF;
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bcdint nib4 = (in >> 16) & 0xF;
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bcdint nib5 = (in >> 20) & 0xF;
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bcdint nib6 = (in >> 24) & 0xF;
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bcdint nib7 = in >> 28;
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bcdint nib7er = nib7 + 1;
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bcdint nib7_pd = 0x11111111 * nib7;
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bcdint nib7er_pd = 0x11111111 * nib7er;
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bcdint nib10 = in & 0xFF;
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bcdint nib32 = (in >> 8) & 0xFF;
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bcdint nib54 = (in >> 16) & 0xFF;
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bcdint nib76 = in >> 24;
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bcdint nib76er = bcdadd(nib76, 1);
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bcdint nib76_pd = 0x01010101 * nib76;
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bcdint nib76er_pd = 0x01010101 * nib76er;
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bcdint nib3210 = in & 0xFFFF;
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bcdint nib7654 = in >> 16;
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bcdint nib7654er = bcdadd(nib7654, 1);
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bcdint nib7654_pd = 0x00010001 * nib7654;
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bcdint nib7654er_pd = 0x00010001 * nib7654er;
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bcdint r = nib7er_pd;
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if (nib7_pd > in) r = MIN(r,nib7_pd);
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if (nib76er_pd > in) r = MIN(r,nib76er_pd);
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if (nib76_pd > in) r = MIN(r,nib76_pd);
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if (nib7654er_pd > in) r = MIN(r,nib7654er_pd);
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if (nib7654_pd > in) r = MIN(r,nib7654_pd);
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return r;
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}
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static
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bcdint next_palindrome_part2(struct id s) {
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if (s.len == 2) return next_palindrome_len2(s.v);
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else if (s.len == 3) return next_palindrome_len3(s.v);
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else if (s.len == 4) return next_palindrome_len4(s.v);
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else if (s.len == 6) return next_palindrome_len6(s.v);
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else if (s.len == 8) return next_palindrome_len8(s.v);
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unsigned len = s.len;
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bcdint in = s.v;
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bcdint best = -1;
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for (unsigned i = 2; i <= len; i++) {
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if (len % i == 0) {
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unsigned high_shift = (len / i) * 4;
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bcdint high = in >> (high_shift * (i - 1));
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for (int j = i - 2; j >= 0; j--) {
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bcdint low = (in >> (high_shift * (j))) & ((1 << high_shift) - 1);
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if (low < high) {
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break;
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} else if (low > high) {
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high = bcdadd(high, 1);
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break;
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}
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}
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bcdint next = 0;
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for (unsigned j = 0; j < i; j++) {
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next |= high << (high_shift * j);
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}
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if (next < best) {
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best = next;
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}
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}
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}
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return best;
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}
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static
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bcdint do_part2(size_t file_len, unsigned char file[file_len]) {
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unsigned char *src = file;
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bcdint result = 0;
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alignas(0x40) struct id ranges[128];
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size_t range_count = 0;
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do {
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unsigned char *tmp;
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bcdint rs = grabbcd(src, &tmp);
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ranges[range_count * 2 + 0] = (struct id) {
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.len = tmp - src,
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.v = rs
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};
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src = tmp + 1;
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bcdint re = grabbcd(src, &tmp);
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ranges[range_count * 2 + 1] = (struct id) {
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.v = re
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};
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src = tmp + 1;
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range_count++;
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} while (src != &file[file_len]);
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do {
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range_count--;
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struct id next = ranges[range_count * 2 + 0];
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bcdint re = ranges[range_count * 2 + 1].v;
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do {
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if (next.len == 1) {
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next = (struct id) { .len = 2, .v = 0x11 };
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} else {
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next.v = next_palindrome_part2(next);
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}
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if (next.v <= re) {
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result = bcdadd(result, next.v);
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}
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bcdint tmp = bcdadd(next.v, 1);
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for (bcdint chk = next.v; chk > 0; chk >>= 4) {
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if ((chk & 0xF) != 9) goto no_len_change;
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}
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next.len++;
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no_len_change:
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next.v = tmp;
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} while (next.v <= re);
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} while (range_count);
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return result;
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}
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void run() {
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print("PART 2 RESULT: ");
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printh(do_part2(countof(input), input));
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print("\n");
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exit_group(0);
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}
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