Objective : Write an algorithm to find two Missing Numbers in a Sequence of Consecutive Numbers
Input: Array, arrA[] with two missing numbers and Range
Output : Two missing numbers
Approach:
- Approach is very simple, Add all the given numbers say S
- Calculate sum of N numbers by formula n(n+1)/2 , say N
- Find sum of two missing numbers a+b = N-S
- Now take the product of all given numbers say P
- Now take the product of N numbers , say Np;
- Find the product of two missing numbers ab = Np-P
- Now we have a+b and ab , we can easily calculate a and b
Example :
Given array : {10,2,3,5,7,8,9,1}; Range : 10
N (Sum of 1 to 10 ) = 55
S (Sum of given elements ) = 45
a+b = 10------------------------------------(1)
Np(Product of 1 to 10) = 3628800
P(Product of given elements) = 151200
So a*b = 24---------------------------------(2)
Now we have two equations and two variables, if we solve we will get values 6 and 4.
Complete Code:
Output:
Missing numbers are :6 and 4
