Python排列组合生成器-优快云博客

本文介绍了一个使用Python实现的排列组合生成器，该生成器能够处理字符可重复、不可重复及全排列的情况，并通过示例代码展示了不同场景下的输出结果。

语言：python

1. 字符可重复

def perm(items, n=None):
    if n is None:
        n = 2
    for i in range(len(items)):
        v = items[i:i+1]
        if n == 1:
            yield v
        else:
            rest = items[:]
            for p in perm(rest, n-1):
                yield v + p
for i in perm("abcdef"):
    print i,

输出结果为：

aa ab ac ad ae af ba bb bc bd be bf ca cb cc cd ce cf da db dc dd de df ea eb ec ed ee ef fa fb fc fd fe ff

2.字符不可重复

def perm(items, n=None):
    if n is None:
        n = 2
    for i in range(len(items)):
        v = items[i:i+1]
        if n == 1:
            yield v
        else:
            rest = items[:i] + items[i+1:]
            for p in perm(rest, n-1):
                yield v + p
for i in perm("abcdef"):
    print i,

输出结果为：

ab ac ad ae af ba bc bd be bf ca cb cd ce cf da db dc de df ea eb ec ed ef fa fb fc fd fe

3.输出全排列

def perm(items, n=None):
    if n is None:
        n = len(items)
    for i in range(len(items)):
        v = items[i:i+1]
        if n == 1:
            yield v
        else:
            rest = items[:i] + items[i+1:]
            for p in perm(rest, n-1):
                yield v + p
for i in perm("abc"):
    print i,

输出结果：

abc acb bac bca cab cba