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Advent of Code 2021

See the full AoC 2021 Day 1 puzzle at the URL: https://adventofcode.com/2021/day/1

My personal objective was to solve the puzzle using the Fortran language.

I dont have much experience with Fortran, so the source code is more verbose than perhaps a simple approach might be, just focusing on just solving the puzzle quickly.

I wanted to learn the use of functions, subroutines, files handling, arrays, and many other new concepts. The resulting programs are the longest and most complex Fortran programs I have written to date.

You have to start somewhere - and AoC Puzzles provides a good purpose to try a language out!

Part ONE:

Task

Count the number of times a depth measurement increases from the previous measurement. There is no measurement before the first measurement. In the example given, the changes are as follows:

199 (N/A - no previous measurement)
200 (increased)
208 (increased)
210 (increased)
200 (decreased)
207 (increased)
240 (increased)
269 (increased)
260 (decreased)
263 (increased)

In this example, there are 7 measurements that are larger than the previous measurement.

Anser needed : How many measurements are larger than the previous measurement?

Build the Fortran Source Code

gfortran -static-libgcc -o aoc_day01_p1 aoc_day01_p1.f90

Part TWO:

Task

Consider sums of a three-measurement sliding window. Again considering the example:

199  A      
200  A B    
208  A B C  
210    B C D
200  E   C D
207  E F   D
240  E F G  
269    F G H
260      G H
263        H

Start by comparing the first and second three-measurement windows. The measurements in the first window are marked A (199, 200, 208); their sum is 199 + 200 + 208 = 607. The second window is marked B (200, 208, 210); its sum is 618. The sum of measurements in the second window is larger than the sum of the first, so this first comparison increased. count the number of times the sum of measurements in this sliding window increases from the previous sum. So, compare A with B, then compare B with C, then C with D, and so on. Stop when there aren't enough measurements left to create a new three-measurement sum.

Anser needed : How many measurements are larger than the previous measurement in this sliding window increase?

Build the Fortran Source Code

gfortran -static-libgcc -o aoc_day01_p2 aoc_day01_p2.f90

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