## 11866 - Triangle

All about problems in Volume 118. If there is a thread about your problem, please use it. If not, create one with its number in the subject.

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Angeh
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Posts: 108
Joined: Sat Aug 08, 2009 2:53 pm

### 11866 - Triangle

How To solve this Problem ...
any idea ??????
>>>>>>>>> A2
Beliefs are not facts, believe what you need to believe;)

sonyckson
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Posts: 49
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Location: Cordoba, Argentina

### Re: 11866 - Triangle

Basically, its easy to count the number of triples you can form with tree numbers between X and Y considering triples as sets (i mean considering (1,2,3) the same as (2,1,3) ). Then you only have to count the number of those triples that can not form a triangle. This means the numbers of triples x, y, z, such that X <= x <= y <= z <= Y such that x + y >= z. Think how can you get a formula for this (i used pre-calculated some values).

Eric.

Angeh
Experienced poster
Posts: 108
Joined: Sat Aug 08, 2009 2:53 pm

### Re: 11866 - Triangle

Thanks for your replay
the number of Triples Between X,Y . is
n=Y-X...
Triples Between X,Y = n*(n+1)*(2n+1)/6
am i right ????????
>>>>>>>>> A2
Beliefs are not facts, believe what you need to believe;)

4085293
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Posts: 5
Joined: Sun Oct 10, 2010 9:52 am

### Re: 11866 - Triangle

OH! I SEE IT'S WRONG BUT I haven't KNOW WHY yet TOO! HELP ME TOO!

phars_alnmr
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Joined: Wed Aug 18, 2010 2:03 am

### Re: 11866 - Triangle

plz could any one post some test cases & its answers

peratu
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Posts: 7
Joined: Sat Jul 10, 2010 9:22 am

### Re: 11866 - Triangle

I have solved that problem, but the judge says "TLE" because I have three loops. I think this problem should be reduced to a "simple" combinatory operation if you want to solve it within the time limit.

peratu
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Joined: Sat Jul 10, 2010 9:22 am

### Re: 11866 - Triangle

phars_alnmr wrote:plz could any one post some test cases & its answers
Sample Input

Code: Select all

``````10
1 10
5 10
5 15
10 20
100 400
100 1000
200 1500
500 10000
1000 15000
1 1000000
``````
Sample Output

Code: Select all

``````125
55
252
285
3898600
79243850
256184575
82185463000
274340382250
83333708333750000
``````