7dan's blog

Invitation to CodeChef Starters 20 (Rated for Div 3) — 15th December
By 7dan, 2 years ago, In English

We invite you to participate in CodeChef’s Starters 20, this Wednesday, 15th December, rated for Div 3 coders.

Time: 8 PM — 11 PM IST

Joining me on the problem setting panel are:

The video editorials of the problems will be available on our YouTube channel as soon as the contest ends. Subscribe to get notifications about our new editorials.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating.

Good Luck!

  • Vote: I like it
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2 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Contest starts in 15 minutes!

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2 years ago, # |
← Rev. 2   Vote: I like it +9 Vote: I do not like it

Can someone give me hints for Finding Pairs?
https://www.codechef.com/START20A/problems/VKMPAIRS

Overall a nice problem set, I liked Weird values and Brutal XORs problem.

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    2 years ago, # ^ |
    ← Rev. 3   Vote: I like it +1 Vote: I do not like it

    Let A[i] be x and A[i] xor B[j] be y .
    So (x*y)%p=1%p
    Since y<p , so y=(x^(-1))%p

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      2 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      y=(x^(-1))%p What is this rule called ?

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        2 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        Multiply both sides by x^(-1) ,
        (y*x*(x^(-1)))%p=(x^(-1))%p

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