python python中的perm算法，带有一个slot对象。

Posted 2021-05-09

#permutation distinct element algorithm

#number of permutations:
import math
def perm_num(n):
    return math.factorial(n)//math.factorial(n-n)

#number of appearances in each slot  
def slot_events(k):
    return perm_num(k)//k
    
def permutations(lst):
    perm_template = []
    perms = []
    slot_max = slot_events(len(lst))
    max_perms = perm_num(len(lst))
    slot_counts = {x:[] for x in range(len(lst))}
    ####

class slot(object):
    
    def __init__(self, value=None):
        self.value = value
        self.memo = []
        if self.value:
            self.memo.append(value)
        
    def __repr__(self):
        return str(self.value)
    def __str__(self):
        return str(self.value)
    def change_val(self, other):
        self.memo.append(other)
        self.value = other