ZIO 2016 Discussion

general
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61

I think you must report this immidiately to madhavan sir’s email address.
It would be really sad to see the honest ones getting rejected and those retards getting selected and having no clue for INOI.

62

Report it. ASAP.
Things were bad for ZCO participants too. Compiler wasn’t working, yes, that bad.

63

Firstly, I’m in Class 9…

I did Question 4 all correct but I’m not sure about Question 1 and 2. 3 screwed up completely (Didn’t take a case into account resulting in wrong answers)

For 1 got 80, 192 and 448. What is supposed to be the correct answer here? (Many people have given different answers)

For 2, 36, 49 and 96. 96 seems to be correct and some other people have got 36 as well (brute force, could have used combinatorics but I kinda screwed up)

Worst case scenario, I’m expecting 25 (96 + Question 4)
Although I think I’ve done Question 2 correctly…

Any ideas about the cutoff? (I hope it is 25…)

64

Yes, these seem correct to me. I wrote a brute force yesterday, and that produced same results. So, unless we have common flaw in logic, it should be correct.

65

Correct answers:

1 - 75, 175, 399

2 - 40, 52, 96

3 - 71, 461, 3447

4 - 13, 10, 12

4 Likes
66

im sure about 75 though not getting it

67

what?       `

1 Like
68

@xorfire Would be great if you also posted how to solve them(or some sort of hint) especially the first and second questions

69

Can anybody provide an explanation for 2 A?

Is it 36 or 40?

Most people have got either 36 or 40 in this thread. Which one is correct?

70

Let X_i = set of all strings such that 11011 occurs at the ith position.

So, for example X_1 is the set of all strings starting with 11011.

Now, the answer is number of elements in (X_1) U (X_2) U …, use inclusion exclusion.

2 Likes
71

@additya1998 Had this problem at our centre too. @lelouch007 , Do report it.

72

I just noticed that you had asked about the second question but I didn’t even read the second question and so, I do not know how to solve it.

73

for first question just count the over countings. S=11011. if aSb=cSd then the string must have conjoined S’s. see the possibilities.
for the second, i counted the possibilities of 0 R, 2 R, 4 R, etc.

74

@ZIO2016:
quedtion 3 can be solved by exclusion and inclusion…any other method

75

@sanket1001 Question 3 can be solved using recursion, the recurrence relation being F(n) = n! - \sum\limits_{i=1}^{n-1} i! \cdot F(n-i)

1 Like
76

Guys the official keys are out! http://www.iarcs.org.in/inoi/2016/zio2016/zio2016-solutions.pdf

1 a. 75   b. 175    c. 399  
2 a. 40   b. 52     c. 96   
3 a. 71   b. 461    c. 3447 
4 a. 13   b. 10     c. 12

Getting 40… class 11. Hope that’s enough to make the cut.

1 Like
77

You’ll definitely go through with a 40.

78

This is my first time and I did quite bad… from what I remember of my answers I’m getting only last question fully right. Can anyone suggest efficient and logical ways of solving the other questions? Even if I arrive at an answer I’m not confident about it.

79

Hey does anyone know the cutoff for class 12 in this year’s ZIO? I am getting 40.

80

When are the results supposed to come? The week’s almost over…