algorithm - 如何找到字符串的排列？

Question

我怎样才能找到特定字符串的组合....

ABCD - "",A,B,C,AB,AC,AD,BC,BD,CD,ABC,ACD,ABD,ABCD,...

C编程语言......

谢谢..

Answer 1

在 set 中插入您需要的字母并调用 findSubset 。

Set findSubsets(Set A)
{
     if A is the empty set
            return the empty set

     // The first element of our set is A[0]
     // (A - A[0] is the set A without the first element)
     Set B := findSubsets(A - A[0])

     // Set B is now all the subsets of A without the first element
     // We now find all the subsets of A containing the first element by finding
     // tacking on the first element to the sets inside B
     Set C = {}
     For each set D in B
            add {A[0], D} to C

    return B added to C
}

Answer 2

在 python 中，标准库ìtertools应该有所帮助。看看combinations()功能，也许其他的取决于你想要什么。您想允许重复吗？顺序重要吗？