Math Problem Statement
Find a solution to the following divide-and-conquer recurrence relations. You may use any method.
For all problems, assume that T(1) = 1.
(1) (Home Work) T(n) = 3T(n/2) + n lg n.
T(1) = 1, T(n) = 3T(n/2) + n log n
let n = 2^k, k = 0,1,2,3,...,infinity
T(2^k) = 3T((2^K)/2) + 2^K (log{2^k})
= 3T(2^{k-1}) + 2k^2 (k) (log{2})
= 3T(2^{k-1}) + k2^k
3T(2^k) - T(2^{k-1}) = k2^k
(x-3)(x-2) = 0
r_1 = 3, r_2 =2
general solution: T(2^k) = c_1(3^k) + A(2^k)
finding constants from boundary conditions
k = 0 => T(2^0) = T(1) = 1
k = 1 => T(2^1) = 3T(1) + 2 (log(2)) = 5
k = 0 => c_1 (3^0) + A(2^0) = 1
k = 1 => c_1 (3^1) + A(2^1) = 5
solving for the constants c_1 = 3, A = -2
T(2^k) = 3(3^k) + -2(-2^k)
since n=2^k => k = log_2{n}
T(n) = 3(3^{log_2 n}) + -2(2^{log_2} n)
is it correct? if not then correct it
Solution
Let's solve the recurrence relation with the base case using the Master Theorem.
Step 1: Identify the Components
The recurrence has the form:
where:
Step 2: Calculate
We first compute :
This means:
Step 3: Compare with
Next, we need to compare with :
- Finding : Since is approximately , we have:
- Comparing and :
We see that:
This means grows slower than .
Step 4: Apply the Master Theorem
Since is polynomially smaller than :
We can apply Case 1 of the Master Theorem:
Step 5: Final Result
Thus, we conclude:
Summary
Your approach started correctly with the recurrence relation but had some errors in the derivation of constants and final expressions. The correct solution is:
Would you like more details on any specific part of the solution? Here are some related questions:
- What are the implications of the result for algorithms using this recurrence?
- How would you solve a similar recurrence with different coefficients?
- Can you explain the different cases of the Master Theorem?
- How does the term affect the overall complexity?
- What would happen if were instead ?
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Math Problem Analysis
Mathematical Concepts
Recurrence Relations
Divide and Conquer
Asymptotic Analysis
Formulas
T(n) = aT(n/b) + f(n)
n^{log_b a}
Master Theorem
Theorems
Master Theorem
Suitable Grade Level
Grades 10-12
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