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Implement day 04.

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Bert Peters
2019-12-04 07:59:18 +01:00
parent b31d56c4ac
commit 8a431820b0
2 changed files with 87 additions and 2 deletions
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1
2019/inputs/04.txt Normal file
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2019/src/day04.cpp
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@@ -1,10 +1,94 @@
#include <iostream>
#include <utility>
#include "days.hpp"
namespace {
constexpr bool is_valid_pass(int num) {
bool has_double = false;
int prev = 11;
for (; num != 0; num /= 10) {
int digit = num % 10;
if (digit == prev) {
has_double = true;
}
if (digit > prev) {
return false;
}
prev = digit;
}
return has_double;
}
constexpr bool is_valid_pass2(int num) {
int prev = 11;
bool has_double = false;
int run = 1;
for (; num != 0; num /= 10) {
int digit = num % 10;
if (digit == prev) {
++run;
} else {
if (run == 2) {
has_double = true;
}
run = 1;
}
if (digit > prev) {
return false;
}
prev = digit;
}
return has_double || run == 2;
}
std::pair<int, int> read_input(std::istream& input) {
int a, b;
input >> a;
input.ignore();
input >> b;
return {a, b};
}
}
void aoc2019::day04_part1(std::istream &input, std::ostream &output) {
output << "Not implemented\n";
auto [start_range, end_range] = read_input(input);
int num_valid = 0;
for (; start_range <= end_range; ++start_range) {
num_valid += is_valid_pass(start_range);
}
output << num_valid << std::endl;
}
void aoc2019::day04_part2(std::istream &input, std::ostream &output) {
output << "Not implemented\n";
auto [start_range, end_range] = read_input(input);
int num_valid = 0;
for (; start_range <= end_range; ++start_range) {
num_valid += is_valid_pass2(start_range);
}
output << num_valid << std::endl;
}
// Poor man's unit tests
static_assert(is_valid_pass(122345));
static_assert(is_valid_pass(111111));
static_assert(!is_valid_pass(223450));
static_assert(!is_valid_pass(123678));
static_assert(is_valid_pass2(112233));
static_assert(!is_valid_pass2(123444));
static_assert(is_valid_pass2(111122));