Midterm 2 Solutions


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Unformatted text preview: ckHeap(A, currentSize, 2*j+1); } else return true; } 8) Recall that we presented an algorithm to remove a key at position j (which is also described in the text.) Here is another possible way to remove a key at position j: move the key at A[currentSize] to A[j] and call percolateDown (j). Will this work? If so, prove it. Otherwise, give an example for which it fails. 8 points Solution: Consider a heap of size 6 containing 1 10 2 12 15 3. Let j = 4. It is easy to see that in this case the above algorithm fails. 9) Write a procedure to delete the second smallest key from a min heap. Your procedure should perform only a constant number of additional operations besides calling INSERT or DELETEMIN. (It should return the second smallest key.) What is the complexity of your procedure? Express your answer using O notation in terms of N = the number of nodes in the heap. 8 points Solution: deleteSecondMin( ) { int temp1 = deleteMin(); int temp2 = deleteMin(); insert(temp1); return temp2; } Time complexity = 3 x O(log n) = O(log n)...
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