Using Figure 8.2 as a model, illustrate the operation of COUNTING-SORT on the array A = [6, 0, 2, 0, 1, 3, 4, 6, 1, 3, 2].
Prove that COUNTING-SORT is stable.
COUNTING-SORT最后是从后面往前面扫，并且把遇到的每一个item放在同大小(key)的最后面的位子.所以不改变相对顺序.
Suppose that the for loop header in line 9 of the COUNTING-SORT procedure is rewritten
as 9 for j ← 1 to length[A]
Show that the algorithm still works properly. Is the modified algorithm stable?
可以正常工作，只是不stable.
Describe an algorithm that, given n integers in the range 0 to k, preprocesses its input and then answers any query about how many of the n integers fall into a range [a...b] in O(1) time. Your algorithm should use Θ(n + k) preprocessing time.
利用数组C,[a,b]间的个数是C[b]-C[a-1].(C[-1] = 0)
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