Archives for the month of: June, 2012

Problems 18 and 67 of Project Euler were the most interesting ones to me, as I almost brute forced them and yet without taking twenty billion years as claimed.
Here’s the problem
By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23.

3
7 4
2 4 6
8 5 9 3

That is, 3 + 7 + 4 + 9 = 23.

Find the maximum total from top to bottom of the triangle below:

75
95 64
17 47 82
18 35 87 10
20 04 82 47 65
19 01 23 75 03 34
88 02 77 73 07 63 67
99 65 04 28 06 16 70 92
41 41 26 56 83 40 80 70 33
41 48 72 33 47 32 37 16 94 29
53 71 44 65 25 43 91 52 97 51 14
70 11 33 28 77 73 17 78 39 68 17 57
91 71 52 38 17 14 91 43 58 50 27 29 48
63 66 04 68 89 53 67 30 73 16 69 87 40 31
04 62 98 27 23 09 70 98 73 93 38 53 60 04 23

NOTE: As there are only 16384 routes, it is possible to solve this problem by trying every route. However, Problem 67, is the same challenge with a triangle containing one-hundred rows; it cannot be solved by brute force, and requires a clever method! ;o)

Here is my analogy to solve this problem,


And here’s my solution in Python

	n = []
	for i in range(15):
		n.append(map(int,raw_input().split()))
	newresult = n.pop(0)
	for i in range(14):
		x = n.pop(0)
		result = list(newresult)
	#	print len(result)
		newresult =[]
		t = len(x)
		for j in range(t):
			if(j==0):
				newresult.append(result[0]+x.pop(0))
			elif(j==t-1):
				newresult.append(result[0]+x.pop(0))
			else:
				newresult.append(max((result.pop(0)+x[0]),result[0]+x.pop(0)))
		print newresult
	print max(newresult)

I essentially keep a list of all possible values by limiting to the max at each step, isn’t that amazing 😉

Really “don’t discount your education”

Rachel Lim's Blog

There was a great question on Programmers about graduating with a programming degree, but not knowing how to program. I see this kind of question a lot, and I felt the same way when I first got my degree, so I thought I’d write about my experiences and what I learned when first started programming.

This was originally an article I wrote for the Programmers.SE blog, however the blog doesn’t appear to be happening at this time so I am posting it on my own blog instead.


Start with baby steps

First off, don’t expect to be able to code enterprise-level applications or the next Facebook right away. You really can’t become a good programmer without a lot of practice, so practice any way you can. This can include hobby projects, reading books or source code, or even answering questions on Stack Overflow.

The book Outliers: The Story of…

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