287. Find the Duplicate Number

#1

Hi! I couldn’t understand how to reach to an optimal approach in this leetcode question please help.

#2

hello @rachitbansal2500

let say x is sum of element of the array.
and y is the number that is repeated .
so we can write it as
x = (n)*(n+1)/2 + y

now
y=x- n*(n+1)/2

x is known ,n is know so using their values we can find y. efficiently

#3

The question states that the number might be repeated more than once, what to do in that case?

#4

refer floyd algorithm (that u have learnt in linked list)

also detailed solution is mention in the solution tab, so u can refer that as well.

#5

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