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#include <cstddef>
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
vector<vector<long>>
read_file(string_view filename)
{
fstream input{ filename };
vector<vector<long>> lines;
auto split = [](const string& str) {
stringstream sstr{ str };
vector<long> values;
for ( long value = 0; sstr >> value; ) {
values.emplace_back(value);
}
return values;
};
for ( string line; getline(input, line); ) {
lines.emplace_back(split(line));
}
return lines;
}
bool
is_safe(const vector<long>& values)
{
vector<long> diffs;
for ( size_t i = 1; i < values.size(); ++i ) {
diffs.emplace_back(values.at(i) - values.at(i - 1));
}
auto all_negative = ranges::all_of(diffs, [](auto diff) { return diff >= -3 && diff < 0; });
auto all_positive = ranges::all_of(diffs, [](auto diff) { return diff <= 3 && diff > 0; });
return all_positive || all_negative;
}
void
part1(const vector<vector<long>>& lines)
{
cout << ranges::count_if(lines, is_safe) << endl;
}
void
part2(const vector<vector<long>>& lines)
{
long safe_count = 0;
for ( const auto& line: lines ) {
auto safe = false;
for ( size_t i = 0; i != line.size(); ++i ) {
auto copy = line;
copy.erase(copy.begin() + ptrdiff_t(i));
safe |= is_safe(copy);
}
if ( safe ) {
++safe_count;
}
}
cout << safe_count << endl;
}
int
main()
{
auto lines = read_file("data/day02.txt");
part1(lines);
part2(lines);
}
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