To determine the worst-case time complexity, we trace all execution paths through the flowchart to find the path that executes the maximum number of recursive calls of size n/2:
From Start, there is 1 recursive call A(n/2).
At the first decision diamond:
Left branch: 1 recursive call A(n/2) and returns ⟹1+1=2 calls total.
Right branch: 2 recursive calls A(n/2), bringing the total so far to 1+2=3 calls, followed by the second decision diamond.
At the second decision diamond:
Right branch: Returns immediately ⟹3 calls total.
Down branch: 1 recursive call A(n/2), followed by the third decision diamond ⟹3+1=4 calls so far.
At the third decision diamond:
Left branch: 1 recursive call A(n/2) and returns ⟹4+1=5 calls total.
Right branch: Returns immediately ⟹4 calls total.
The worst-case path executes a total of 5 recursive calls of size n/2. Thus, the recurrence relation for the worst-case time complexity is:
T(n)=5T(2n)+O(1) Using the Master Theorem for T(n)=aT(n/b)+f(n) where a=5, b=2, and f(n)=O(1):
c=logba=log25≈ln2ln5≈0.69311.6094≈2.32 Since f(n)=O(n0) and 0<log25, the worst-case time complexity is Θ(nlog25)=Θ(n2.32).
Therefore, the least possible value of α is 2.32 (accepted range: 2.2 to 2.4).