Practice Set for Recurrence Relations

Recurrence relations are equations that recursively defines a multidimensional array.

Here we will solve so questions based on recurrence relations.

Solve the recurrence reation:T(n) = 12T(n/2) + 9n2 + 2.
T(n) = 12T(n/2) + 9n2 + 2.
Here, a = 12 and b = 2 and f(n) = 9(n)2 + 2
It is of the form f(n) = O(n^c), where c = 2

This form its in the master’s theorem condition,

So,
logb(a) = log2(12) = 3.58
Using case 1 of the masters theorm, T(n) = θ(n3.58).

Solve the recurrence reation:T(n) = 5T(n/2 + 23) + 5n2 + 7n - 5/3.
T(n) = 5T(n/2 + 23) + 5n2 + 7n - 5/3

On simplification, in case of large values, n,n/2 >> 23, so 23 is neglected.

T(n) = 5T(n/2) + 5n2 + 7n - 5/3.
Further, we can take 5n2 + 7n - 5 ≃0(n2).
So, T(n) = 5T(n/2) + O(n2)

This fall under the case 2 of masters theorem,

So, T(n) = O(n2).

Check if the following comes under any case of a master’s theorem.

T(n) = 2T(n/3) + 5n

No, For masters theorem to be applied, the function should be a polynomial function.

T(n) = 2T(n/5) + tan(n)

No, trignometric function do not come under masters theorem.

T(n) = 5T(n+1) + log(n)

No, Logarithmic function do not come under masters theorem.

T(n) = T(n-7) + en

No, exponential function do not come under masters theorem.

T(n) = 9n(n/2+1 ) + 4(n2) - 17
Yes, as solved above.

sudhir sharma

Updated on: 04-Feb-2020

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