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#include "aoc.h"
namespace aoc2021 {
int decimal(const char* p) {
int d{0};
while (*p == '0' || *p == '1') {
d = 2 * d + *p - '0';
p++;
}
return d;
}
int day3(line_view file) {
char gamma[13] = {0};
char epsilon[13] = {0};
int is[12] = {0};
int total{0};
per_line(file, [&is, &total](line_view lv) {
for (int i = 0; i < 12; i++) {
if (*(lv.line + i) == '1') {
is[i] += 1;
}
}
total += 1;
return true;
});
for (int i = 0; i < 12; i++) {
if (is[i] > total / 2) {
gamma[i] = '1';
epsilon[i] = '0';
} else {
gamma[i] = '0';
epsilon[i] = '1';
}
}
// printf("%s\n", gamma);
// printf("%s\n", epsilon);
return decimal(gamma) * decimal(epsilon);
}
} // namespace aoc2021
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