
Sum it on
http://www.techinterview.org/Solutions/fog0000000101.html
You may use the following:
if x1, x2, x3, x4 ... xN are your numbers, where x1=1,
and x2=2, etc.. and one number repeats once, you may
do this:
Sum(x1,...,xN)  xN(xN+1)/2 > will give you the duplicate.
Adel
Thursday, October 16, 2003
what if you just get:
(x1 + x2 + ... + xN)  (x1 + x2 + ... + x(N1) )
sag3
Wednesday, October 22, 2003
Basically, if you are given 5 numbers (lets say 1 2 2 3 4 )
Then, Sn=sum of first 5 natural numbers = n* (n+1)/2 = 15
Now, add the given numbers to get Sx=1+2+2+3+4=12
d=SnSx=3
and nd=repeated number=53=2
Thus in nutshell,
Repeated number= N  (SnSx)
where,
Sn=Sum of first N natural numbers starting from 1
Sx=Sum of the given series containing a repeated number
aha!
:)
Gaurav Sachdeva
Monday, December 15, 2003
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