比方说，我有一个数组 A 长度 N 和第二阵列指数，也长 N 。 指数包含了一些任意的排列顺序 [0，N）。我想重新排列 A 这样的，它是由指数指定的顺序。例如，用D-语法：

Let's say I have an array a of length n and a second array indices, also of length n. indices contains some arbitrary permutation of the sequence [0, n). I want to to rearrange a such that it's in the order specified by indices. For example, using D syntax:

auto a = [8, 6, 7, 5, 3, 0, 9];
auto indices = [3, 6, 2, 4, 0, 1, 5];
reindexInPlace(a, indices);
assert(a == [5, 9, 7, 3, 8, 6, 0]);

这个问题能在这两个O（1）空间和O（n）的时间，preferably没有突变指标完成？

推荐答案

通过变异指数 :(。如果没有看起来很难（见稳定就地合并排序）。

With mutating indices :(. Without looks hard (see stable in-place mergesort).

a = [8, 6, 7, 5, 3, 0, 9]
indices = [3, 6, 2, 4, 0, 1, 5]

for i in xrange(len(a)):
    x = a[i]
    j = i
    while True:
        k = indices[j]
        indices[j] = j
        if k == i:
            break
        a[j] = a[k]
        j = k
    a[j] = x

print a