Another two days down, no sweat (minus a segfault on day 6, but shhhh.)

Day 5’s challenge was to take a list of jump offsets and determine how many jumps you need to take before exiting the block of code (modifying the jump offsets each time)

Day 6’s challenge was to take a list of memory banks, run through a balancing algorithm regarding allocations, and count how many steps until an infinite loop.

Let’s take a look at the code, as they clock in at <40 lines apiece.

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Hooray, another easy one.  After Day number 3, I could certainly use it.  This challenge involved taking a list of passphrases, and counting up the number of passphrases that had no duplicate words.   This seems simple, just a split, sort and application of std::unique.

Part 2 had me check for anagrams rather than duplicate words.  This was also easy, as I could map over a sort function to each word in the passphrase, and then check for uniqueness.

Let’s look at the code

#include <algorithm>
#include <iostream>
#include <string>

#include "algo.h"
#include "input.h"

std::string sortString(std::string s) {
    std::sort(s.begin(), s.end());
    return s;
}

bool isUnique(const std::string& passphrase) {
    auto words = algo::map(input::split(passphrase), sortString);
    std::sort(words.begin(), words.end());
    return words.end() == std::unique(words.begin(), words.end());
}

int main() {
    auto passPhrases = input::readMultiLineFile("input/input04.txt");
    auto count = std::count_if(passPhrases.begin(), passPhrases.end(), isUnique);
    std::cout << count << "\n";
    return 0;
}

Super straight forward.  I think the trickiest thing was std::unique, because I didn’t realize it returned the end iterator of the range.  But once I figured that out, this wasn’t so bad.

Stay tuned for day 5!

So this day was a tad bit rougher.  I wasn’t expecting the sudden difficulty increase on day 3.  The problems were straight-forward enough, but I didn’t want to brute force my way through them.  Unfortunately, I didn’t get the math worked out, so brute force became one of my last options

However, on the bright side, I got to play with std::optional, so I got that going for me.

I’m going to have a tough time explaining the problem any better than advent of code, so I’m just going to link you there instead

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It’s December and you know what that means!  Advent Of Code is back!.

This year, I’m not going to try the 25 languages in 25 days, but instead focus on my C++ skills.  More specifically, here are the constraints I am putting on myself.

• Use C++17 where I can if it makes sense
• Avoid raw loops on containers unless I have a performance concern
• If there are any raw loops needed, see if it can be abstracted into a generic algorithm

So Challenge 1: here we go. Continue reading →