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#include "aoc.h"
#include <vector>
namespace aoc2018 {
int exactly(const ascii_count& ac, int x) {
for (char i = 'a'; i <= 'z'; i++) {
if (ac.count[int(i)] == x) {
return 1;
}
}
return 0;
}
bool almost(line_view lv1, line_view lv2, char comm[]) {
const char* p1 = lv1.line;
const char* p2 = lv2.line;
int x{0};
int i{0};
while (p1 < lv1.line + lv1.length - 1 && x < 2) {
if (*p1 == *p2) {
comm[i++] = *p1;
} else {
x++;
}
p1++;
p2++;
}
return x == 1;
}
void diff(size_t i, const std::vector<line_view>& ls, char comm[]) {
if (i < ls.size() - 1) {
for (size_t j = i + 1; j < ls.size(); j++) {
if (almost(ls[i], ls[j], comm)) {
return;
}
}
diff(i + 1, ls, comm);
}
}
int day2(line_view file, char comm[]) {
int exactly2{0};
int exactly3{0};
std::vector<line_view> ls;
per_line(file, [&exactly2, &exactly3, &ls](line_view lv) {
ls.push_back(lv);
ascii_count ac(lv);
exactly2 += exactly(ac, 2);
exactly3 += exactly(ac, 3);
return true;
});
diff(0, ls, comm);
return exactly2 * exactly3;
}
} // namespace aoc2018
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