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#include "aoc.h"
#include <stack>
namespace aoc2015 {
int get_number(const char* p1, const char* p2) {
int sign = *(p1 - 1) == '-' ? -1 : 1;
int d{0};
while (p1 != p2) {
d = d * 10 + *p1 - '0';
p1++;
}
return sign * d;
}
int parse_day12(line_view s) {
int total = 0;
const char* p1 = s.line;
const char* p2 = p1;
bool to_parse = false;
while (p2 < s.line + s.length) {
if (*p2 >= '0' && *p2 <= '9') {
if (!to_parse) {
p1 = p2;
to_parse = !to_parse;
}
} else {
if (to_parse) {
total += get_number(p1, p2);
to_parse = !to_parse;
}
}
p2++;
}
if (to_parse) {
total += get_number(p1, p2);
}
return total;
}
int day12(line_view file) { return parse_day12(file); }
struct day12_object {
const char* p1;
int fold(const char* p2) {
line_view lv{p1, p2};
const char* p = lv.contains("red");
return (p != nullptr) ? 0 : parse_day12(lv);
}
};
// {{x} x} = 0
// {{x} ...} = ...
// {{...} x} = 0
// {{...} .} = ... + .
int day12_part2(line_view file) {
int total = 0;
std::stack<day12_object> os;
std::stack<int> is;
const char* p = file.line;
const char* p1 = p;
while (p < file.line + file.length) {
if (*p == '{') {
if (os.empty()) {
total += parse_day12({p1, p});
p1 = p;
}
os.push({p});
}
if (*p == '}') {
auto o = os.top();
is.push(o.fold(p));
os.pop();
if (os.empty()) {
while (!is.empty()) {
total += is.top();
is.pop();
}
p1 = p;
} else {
auto& oo = os.top();
oo.p1 = p;
}
}
p++;
}
total += parse_day12({p1, p});
return total;
}
} // namespace aoc2015
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