GATE | GATE CS 1999 | Question 46
If T1 = O(1), give the correct matching for the following pairs:
(M) Tn=Tn−1+n (U) Tn=O(n)
(N) Tn=Tn/2 +n (V) Tn=O(nlogn)
(O) Tn=Tn/2 +nlogn (W) T=O(n^2)
(P) Tn=Tn−1 +logn (X) Tn=O(log^2n)
(A) M-W N-V O-U P-X
(B) M-W N-U O-X P-V
(C) M-V N-W O-X P-U
(D) M-W N-U O-V P-X
Answer:
Explanation:
(M) T(n) = T(n-1) + n = 1 + 2 + 3 + … + n = O(n^2) — choice is (W)
(N) T(n) = T(n/2) + n = O(n), using master theorem case -3, - choice is (U)
(O) T(n) = T(n/2) + nlogn = O(nlogn), using master theorem case -3, - choice is (v)
(P) T(n) = T(n-1) + logn = log 1 + log 2 + log 3 + … + log n
= log(1*2*3…*n) = log(n!) = nlogn = O(nlogn) - choice is (v)
Therefore, none option matches.
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Last Updated :
12 Sep, 2018
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