Provide the solution for the following recurrence: T(n) = 2T(n/2) + logn
Q.) Provide the solution for the following recurrence: T(n) = 2T(n/2) + logn
Subject: Data Structures - IIRecurrence Relation:
$$T(n) = 2T(n/2) + \log n$$
Solution:
To solve this recurrence relation, we can use the following steps:
- Guess the form of the solution:
Based on the recurrence relation, we can guess that the solution is of the form:
$$T(n) = a \log n + b$$
where a
and b
are constants.
- Verify the guess:
To verify the guess, we need to substitute it into the recurrence relation and see if it holds.
Substituting the guess into the recurrence relation, we get:
$$a \log(\frac{n}{2}) + b = 2(a \log(\frac{n}{2}) + b) + \log n$$
Simplifying the equation, we get:
$$(a-2a) \log(\frac{n}{2}) + (b-2b) = \log n$$
$$-a \log(\frac{n}{2}) - b = \log n$$
$$a \log n + b = \log n$$
$$a = 1$$
$$b = 0$$
Therefore, the guess is correct.
- Final Solution:
The final solution to the recurrence relation is:
$$T(n) = \log n$$
- Complexity Analysis:
The complexity of the solution is O(log n)
. This is because the recurrence relation has a constant number of subproblems, and each subproblem is solved in O(1)
time. Therefore, the total time complexity is O(log n)
.