In my eyes, it shouldn't make a difference. Adding 1 + 2 is the same as adding 2 + 1 right? so you just get the range and add all numbers together to find the total, so I'm not sure why you're multiplying there Cervantes
Computer Science Canada Open Language TYS |
| Author: | wtd [ Thu Feb 15, 2007 9:42 am ] |
| Post subject: | Open Language TYS |
Write a function which sums an inclusive range of numbers. Bonus points for efficiency. |
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| Author: | Cervantes [ Thu Feb 15, 2007 11:54 am ] | ||
| Post subject: | RE:Open Language TYS | ||
Maybe I don't understand the question, because here's my solution:
Are we supposed to take into account negative numbers too, I suppose? |
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| Author: | Clayton [ Thu Feb 15, 2007 12:16 pm ] |
| Post subject: | Re: Open Language TYS |
In my eyes, it shouldn't make a difference. Adding 1 + 2 is the same as adding 2 + 1 right? so you just get the range and add all numbers together to find the total, so I'm not sure why you're multiplying there Cervantes |
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| Author: | Hikaru79 [ Thu Feb 15, 2007 12:35 pm ] |
| Post subject: | Re: Open Language TYS |
Freakman @ Thu Feb 15, 2007 1:16 pm wrote: In my eyes, it shouldn't make a difference. Adding 1 + 2 is the same as adding 2 + 1 right? so you just get the range and add all numbers together to find the total, so I'm not sure why you're multiplying there Cervantes
He's using the identity that the sum of the first n consecutive numbers is n(n+1)/2. This gives us an almost constant-time solution to wtd's TYS, which also leads me to think he meant something else. Cervantes' solution is also what I would have done; it's just too easy  |
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| Author: | wtd [ Thu Feb 15, 2007 12:52 pm ] |
| Post subject: | RE:Open Language TYS |
No no... you got the right answer.  |
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| Author: | Clayton [ Thu Feb 15, 2007 1:39 pm ] |
| Post subject: | Re: Open Language TYS |
Shows how little I know, and how much I need to learn |
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| Author: | Cervantes [ Thu Feb 15, 2007 3:31 pm ] |
| Post subject: | Re: Open Language TYS |
This reminds me of a problem I liked, stolen from Project Euler: Quote: The palindromic number 595 is interesting because it can be written as the sum of consecutive squares: 6^2 + 7^2 + 8^2 + 9^2 + 10^2 + 11^2 + 12^2. There are exactly eleven palindromes below one-thousand that can be written as consecutive square sums, and the sum of these palindromes is 4164. Note that 1 = 0^2 + 1^2 has not been included as this problem is concerned with the squares of positive integers. Find the sum of all the numbers less than 10^8 that are both palindromic and can be written as the sum of consecutive squares. |
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