Aren't Project Euler's exercises seem more likely maths exercises? It's kinda difficult for those who graduated from social sciences and tries to learn programming from scratch.
Project Euler does involve a math, but so does efficient programming.
Efficiency can seem a pretty abstract thing and it might not crop up right away in more typical programming tasks. Working a Euler problem and refining to a solution that runs in 1% or 0.001% of the time required for the most straightforward solution is a great demonstrator.
>It's kinda difficult for those who graduated from social sciences and tries to learn programming from scratch.
Sure, but the context of the question here isn't really from scatch. The OP has already completed at least the 296 exercises in the Python track at Codeacademy to establish a base.
Personally, I haven't graduated from anything and I treat the Euler exercises as an interesting way to practice/learn a bit of programming and math.
Think Python: How To Think Like a Computer Scientist http://www.greenteapress.com/thinkpython/thinkpython.html
Think Complexity: Exploring Complexity Science with Python : http://www.greenteapress.com/compmod/
Think Stats: Probability and Statistics for Programmers : http://www.greenteapress.com/thinkstats/index.html