229 lines
6.2 KiB
C
229 lines
6.2 KiB
C
#include "lib.h"
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static
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ch input[] = {
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#embed "day6_input.txt"
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};
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static
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ch test[] = {
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#embed "day6_test.txt"
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};
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typedef struct { ch l[64]; } line;
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static_assert(sizeof(line) == 0x40);
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alignas(0x40) static
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struct {
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line padstart[4];
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struct { num pad[3]; num prev_op_off, op_off, ledge_off, redge_off, rem; };
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union { line l; struct { ch s[16]; num op, pad0, pad1, v; }; } b;
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union { line l; struct { ch s[16], pad0, sr[16], pad1; num v, vr; }; } a;
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line padend;
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} m;
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static_assert(offsetof(typeof(m),b) % 64 == 0);
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static_assert(sizeof(m.b) == 64);
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static_assert(sizeof(m.a) == 64);
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static_assert(offsetof(typeof(m),padend) % 64 == 0);
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static
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num do_part1(size_t file_len, ch file[file_len]) {
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ch *s = file;
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m = (typeof(m)){ };
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s = memchr(s, '\n', file_len);
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const num stride = s - file;
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s = file;
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while (*s != '+' && *s != '*') s += stride;
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const num heightb = (s - file);
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const num height = (s - file) / stride;
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ch *const op = s;
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// constructing a pointer more than 1 past the end of an array
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// is UB, sadly, so we'll use offsets
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m.op_off = op - file;
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s = file;
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do {
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m.ledge_off = m.op_off - heightb;
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if (s[m.op_off] == '+') {
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m.a.v = 0;
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m.rem = height;
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m.b.op = '+' << 8;
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snprintd(m.a.v, 16, m.a.s);
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do {
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ch *t = s + m.ledge_off;
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while (*t < '0') t++;
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m.b.v = grabnum(t, NULL);
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snprintd(m.b.v, 16, m.b.s);
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m.a.v += m.b.v;
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snprintd(m.a.v, 16, m.a.s);
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m.ledge_off += stride;
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m.rem--;
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} while (m.rem);
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m.a.vr += m.a.v;
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snprintd(m.a.vr, 16, m.a.sr);
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} else if (s[m.op_off] == '*') {
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m.a.v = 1;
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m.rem = height;
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m.b.op = '*' << 8;
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snprintd(m.a.v, 16, m.a.s);
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do {
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ch *t = s + m.ledge_off;
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while (*t < '0') t++;
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m.b.v = grabnum(t, NULL);
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snprintd(m.b.v, 16, m.b.s);
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m.a.v *= m.b.v;
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snprintd(m.a.v, 16, m.a.s);
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m.ledge_off += stride;
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m.rem--;
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} while (m.rem);
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m.a.vr += m.a.v;
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snprintd(m.a.vr, 16, m.a.sr);
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}
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m.op_off++;
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while (m.op_off < file_len) {
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if (s[m.op_off] == '+' || s[m.op_off] == '*')
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break;
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m.op_off++;
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}
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} while (m.op_off < file_len);
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return m.a.vr;
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}
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static
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num do_part2(size_t file_len, unsigned char file[file_len]) {
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ch *s = file;
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m = (typeof(m)){ };
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s = memchr(s, '\n', file_len);
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const num stride = s - file;
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s = file;
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while (*s != '+' && *s != '*') s += stride;
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const num heightb = (s - file);
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const num height = (s - file) / stride;
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ch *const op = s;
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// constructing a pointer more than 1 past the end of an array
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// is UB, sadly, so we'll use offsets
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const num fop_off = op - file;
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m.prev_op_off = fop_off + stride - 1;
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s = file;
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do {
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// we don't need to do these in the same order as the example
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// because both these operations are commutative.
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// but you know what? we can anyway. for fun. and pretty output
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{
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num op_off = m.prev_op_off - 1;
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while (s[op_off] != '+' && s[op_off] != '*' && s[op_off] != '\n')
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op_off--;
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m.op_off = op_off;
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}
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m.ledge_off = m.op_off - heightb;
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m.redge_off = (s[m.prev_op_off] == '\n' ? -1 : -2) + m.prev_op_off - heightb;
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if (s[m.op_off] == '+') {
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m.a.v = 0;
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m.rem = m.redge_off - m.ledge_off + 1;
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const num frem = m.rem;
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m.b.op = '+' << 8;
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snprintd(m.a.v, 16, m.a.s);
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do {
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m.b.v = 0;
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ch *t = s + m.redge_off;
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for (num i = height; i; i--,t+=stride) {
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if (*t >= '0') {
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m.b.v *= 10;
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m.b.v += *t - '0';
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}
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}
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snprintd(m.b.v, 16, m.b.s);
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m.a.v += m.b.v;
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snprintd(m.a.v, 16, m.a.s);
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m.redge_off--;
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m.rem--;
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} while (m.rem);
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m.a.vr += m.a.v;
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snprintd(m.a.vr, 16, m.a.sr);
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} else if (s[m.op_off] == '*') {
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m.a.v = 1;
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m.rem = m.redge_off - m.ledge_off + 1;
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const num frem = m.rem;
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m.b.op = '*' << 8;
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snprintd(m.a.v, 16, m.a.s);
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do {
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m.b.v = 0;
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ch *t = s + m.redge_off;
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for (num i = height; i; i--,t+=stride) {
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if (*t >= '0') {
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m.b.v *= 10;
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m.b.v += *t - '0';
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}
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}
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snprintd(m.b.v, 16, m.b.s);
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m.a.v *= m.b.v;
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snprintd(m.a.v, 16, m.a.s);
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m.redge_off--;
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m.rem--;
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} while (m.rem);
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m.a.vr += m.a.v;
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snprintd(m.a.vr, 16, m.a.sr);
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}
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m.prev_op_off = m.op_off;
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} while (m.prev_op_off != fop_off);
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return m.a.vr;
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}
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#define RUN_TEST1 1
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#define RUN_PART1 1
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#define RUN_TEST2 1
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#define RUN_PART2 1
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#define TEST1_EXPECT 4277556
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#define TEST2_EXPECT 3263827
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void run() {
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#if RUN_TEST1
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print("PART 1 TEST: ");
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if (num v = do_part1(countof(test), test); v != TEST1_EXPECT) {
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print("FAILED (got ");
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printd(v);
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print(", expected " xstr(TEST1_EXPECT) ")\n");
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} else {
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print("PASSED\n");
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}
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#endif
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#if RUN_PART1
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print("PART 1 RESULT: ");
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printd(do_part1(countof(input), input));
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print("\n");
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#endif
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#if RUN_TEST2
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print("PART 2 TEST: ");
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if (num v = do_part2(countof(test), test); v != TEST2_EXPECT) {
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print("FAILED (got ");
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printd(v);
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print(", expected " xstr(TEST2_EXPECT) ")\n");
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} else {
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print("PASSED\n");
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}
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#endif
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#if RUN_PART2
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print("PART 2 RESULT: ");
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printd(do_part2(countof(input), input));
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print("\n");
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#endif
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exit_group(0);
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}
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