18 If the time complexity of an algorithm is O (1), it means (1.89) A: With the increase of the scale of the problem, the growth rate of the running time of the algorithm is 1 B. The running time of the algorithm is 1s The number of basic operations in the algorithm is independent of the data size of the problem D. The algorithm contains only one basic operation 24 A tree with degree 7 has 7 nodes with degree 2, 6 nodes with degree 3, 5 nodes with degree 4.4 nodes with degree 5, 3 nodes with degree 6, and 2 nodes with degree 7. How many leaf nodes does the tree have? (1.85) A B. 28 C. 78 D 35 12 14 Data structure is the basic unit of data. 16 20 24 (1.01) 4 8