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#include "aoc.h"
#include <vector>
namespace aoc2016 {
bool is_abba(const char* p) { return *p == *(p + 3) && *(p + 1) == *(p + 2) && *p != *(p + 1); }
bool is_aba(const char* p) { return *p == *(p + 2) && *p != *(p + 1); }
bool is_reverse(const char* p1, const char* p2) { return *p1 == *(p2 + 1) && *(p1 + 1) == *p2; }
std::vector<line_view> aba(const std::vector<line_view>& ls) {
std::vector<line_view> vs;
for (auto& l : ls) {
const char* p = l.line;
while (p < l.line + l.length - 2) {
if (is_aba(p)) {
vs.emplace_back(p, 3);
}
p++;
}
}
return vs;
}
bool match_aba(const std::vector<line_view>& ls1, const std::vector<line_view>& ls2) {
for (auto& l1 : ls1) {
for (auto& l2 : ls2) {
if (is_reverse(l1.line, l2.line)) {
return true;
}
}
}
return false;
}
bool has_abba(const std::vector<line_view>& ls) {
for (auto& l : ls) {
const char* p = l.line;
while (p < l.line + l.length - 3) {
if (is_abba(p)) {
return true;
}
p++;
}
}
return false;
}
std::pair<int, int> day7(line_view file) {
int t0{0}, t1{0};
per_line(file, [&t0, &t1](line_view lv) {
std::vector<line_view> g1;
std::vector<line_view> g2;
const char* p1 = lv.line;
const char* p = p1;
while (p < lv.line + lv.length) {
if (*p == '[') {
g1.emplace_back(p1, p);
p1 = p + 1;
}
if (*p == ']') {
g2.emplace_back(p1, p);
p1 = p + 1;
}
p++;
}
g1.emplace_back(p1, p);
t0 += int(has_abba(g1) && !has_abba(g2));
t1 += int(match_aba(aba(g1), aba(g2)));
return true;
});
return {t0, t1};
}
} // namespace aoc2016
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