The Midlife Geek

Ramblings of a middle aged engineer, runner and open source enthusiast

Tag: R

Euler 15 – How many routes through a 20×20 grid?

Struggled to get my head around Euler problem 15:

Starting at the top left of a 20×20 grid and only moving right and down, how many routes are there?

I figured that this was a combinatorics problem but couldn’t see what to count or choose from.

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Project Euler 19

Project Euler again, problem 19. How many Sundays fell on the first of the month in the twentieth century?

Brute force solution in R but it let me play around with the way R handles dates. Seems more straight forward than in many languages (looking at you Java).

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First 1000 digit Fibonacci number

Project Euler problem 25 is to find the index of the first Fibonacci number of 1000 characters. I used the gmp library – I couldn’t find a way to get the length of a bigz data type so converted it to a string:
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Sum a list of 50 digit numbers

Problem 13 is summing a list of fifty digit numbers. I used the gmp library and R to solve in 2 lines:

library(gmp)
print(substring((sum(as.bigz(readLines("euler13.txt")))), 0, 10))

Not much more to say really. I forgot the problem asks for the first 10 digits, so my first answer was wrong.

First triangular number with 500 divisors

OK so today I’m trying problem 12 – find the first triangular number with over 500 divisors. This is the first Project Euler problem I’ve really struggled to find a solution in a reasonable amount of time. Continue reading

Product of 4 consecutive numbers

I’m beginning to like R. You can capture table data from a connection (a generalised file), one of which is the clipboard, to a data frame.

problem.matrix <- 
    as.matrix(read.table("clipboard",sep=" "))

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Project Euler, Visual Studio and playing with Python

I got Visual Studio 2017 through Microsoft’s Dreamspark promotion and thought I’d give it a try. I haven’t done a lot of development under Windows because its only on my laptop and my Linux desktop has 12 Gb RAM.
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