Latest TCS Aptitude Question SOLUTION: in a sequence of integers, A(n) = A(n-1)- A(n-2)where A(n) is the nth term in the sequence, n is the integer and n>=3, A(1)=1, A(2)=1 calculate S(1000), where S(1000) is the sum of

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in a sequence of integers, A(n) = A(n-1)- A(n-2)where A(n) is the nth term in the sequence, n is the integer and n>=3, A(1)=1, A(2)=1 calculate S(1000), where S(1000) is the sum of first 1000 terms

Asked In TCS Nishant Sanghai (11 years ago)

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Vinod Kumar Prajapati  (11 years ago)

Ans. 1
the sequence is 1,1,0,-1,-1,0,1,1,0,-1,-1,0,.......
so terms are repeated after 6th.hence 1000%6 i.e first 996 will be zero.
the sum of remaining 4 terms is 1

Is this solution Helpfull? Yes (23) | No (2)  

alankargupta  (11 years ago)

A(3)=0
A(4)=-1
A(5)=-1
A(6)=0
A(7)=1
continuing we get a series of 1,1,0,-1,-1,0,1....
the series repeates itself for 6 first digits(1,1,0,-1,-1,0)
so s(1000)=s(6*136)+s(4)
=s(6)*136+s(4)
as the sum of 1st 6 digit is 0 and 1st 4 digit is 1
so =(0*136)+1
=1 :)

Is this solution Helpfull? Yes (10) | No   

goldy  (11 years ago)

1,1,0,-1,-1,0,1,1,0,-1,-1,0.......
here we see that the sum of first 5 nos. is=0
and the series is starting from 1
thus 1000/5=200
that is no term is remaining if we take a combination of 5 nos, where each combination=0.
thus the total value=0
s(1000)=0.

Is this solution Helpfull? Yes (5) | No (8)  

Saurabh Awasthi  (11 years ago)

sum of first 1000 terms will be
S(1000) = -1

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Jana  (11 years ago)

but options are 2,3,4,0.
wich s correct???

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Nishant Sanghai  (11 years ago)

options are
# 2
# 3
# 4
# 0
1 and -1 are not in the options

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prachitrivedi  (11 years ago)

sum of1000 terms will be=1

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BALENDU NARAIN PANDEY  (11 years ago)

-995....as A(3)=0 A(4)=-1 A(5)=-1 A(6)=-2 &SERIES GOES ON so
1+1+0-1+(-1)+(996-1)(-1)=-995

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