Regional BdOI 2013 Questions

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*Mahi*
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Regional BdOI 2013 Questions

Unread post by *Mahi* » Sat Dec 29, 2012 11:02 am

Questions for all the divisions were same.
Also there are some typos in the questions. I hope the contestants can figure them out.
Thanks to Wasi vai for the PDF problemset.
Link:
Problem Set

[Edited the post, because the previous link was broken]
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Re: Regional BdOI 2013 Questions

Unread post by Illusory Time » Sat Dec 29, 2012 4:11 pm

Question 2:(i)
Propose a general method to find the final value of V for any binary number B. How it should be solved?

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Re: Regional BdOI 2013 Questions

Unread post by kfoozminus » Sat Dec 29, 2012 10:41 pm

Illusory Time wrote:Question 2:(i)
Propose a general method to find the final value of V for any binary number B. How it should be solved?
Hint:
find the value of $V$ for first $6$ integers ;)

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Re: Regional BdOI 2013 Questions

Unread post by Illusory Time » Sun Dec 30, 2012 9:19 pm

ঠিক বুজতে পারলাম না। V এর সর্বশেষ মান তো বাইনারি সংখ্যা B এর উপর নির্বর করে। এক একটি বাইনারি সংখ্যার জন্য V এর মান ভিন্ন রকম হতে পারে। V এর সর্বশেষ মান নির্ণয়ের একটি সাধারণ সমাধান কিভাবে নির্ণয় করব? প্রথম কোন ছয়টি পূর্ণ সংখ্যার জন্য V এর মান নির্ণয় করব?

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Re: Regional BdOI 2013 Questions

Unread post by *Mahi* » Sun Dec 30, 2012 10:21 pm

The hint said to find the value for binary equivalents of integers $1-6$ and then make a conjecture.
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Re: Regional BdOI 2013 Questions

Unread post by nafistiham » Mon Dec 31, 2012 8:13 pm

I preferred turning binary into $3$ based number. :lol:
\[\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0\]
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Re: Regional BdOI 2013 Questions

Unread post by Illusory Time » Mon Dec 31, 2012 9:52 pm

nafistiham wrote:I preferred turning binary into $3$ based number. :lol:
বাইনারিকে ৩ ভিত্তিক সংখ্যায় কিভাবে রুপান্তর করা যায়?

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Re: Regional BdOI 2013 Questions

Unread post by nafistiham » Mon Dec 31, 2012 10:03 pm

Illusory Time wrote:
nafistiham wrote:I preferred turning binary into $3$ based number. :lol:
বাইনারিকে ৩ ভিত্তিক সংখ্যায় কিভাবে রুপান্তর করা যায়?
সব ভিত্তি থেকেই সব ভিত্তিতে যাওয়া যায় । কিন্তু, আমরা যেহেতু ১০ ভিত্তিক সংখ্যায় অভ্যস্ত । যেকোনো ভিত্তির সংখ্যাকে অন্য ভিত্তিতে নিতে গেলে মাঝখানে একবার ১০ ভিত্তিতে রুপান্তর করে নিতে পারি ।
১০ ভিত্তিক সংখ্যা থেকে ৩ ভিত্তিকে নেওয়াটা আশা করি ব্যাখ্যা করতে হবে না ।
\[\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0\]
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Re: Regional BdOI 2013 Questions

Unread post by arnob » Fri Jan 04, 2013 5:36 pm

Those were all mathematical methods.... I went with a different approach :D :D :D
Just wrote a code which will do "xor"s .... a lot of "xor"s. As 1 and 0 in the questions gave the exact values xor gives so just returned the value of v again and again till the last. :D :D

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Re: Regional BdOI 2013 Questions

Unread post by nafistiham » Fri Jan 04, 2013 8:25 pm

arnob wrote:Those were all mathematical methods.... I went with a different approach :D :D :D
Just wrote a code which will do "xor"s .... a lot of "xor"s. As 1 and 0 in the questions gave the exact values xor gives so just returned the value of v again and again till the last. :D :D
Nice thinking.
\[\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0\]
Using $L^AT_EX$ and following the rules of the forum are very easy but really important, too.Please co-operate.
Introduction:
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CSE Dept. SUST -HSC 14'
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nafistiham@gmail

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