LeetCode——Permutations

时间:2021-10-25 01:31:53

Permutations

Given a collection of numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3][1,3,2][2,1,3][2,3,1][3,1,2], and [3,2,1].

用Python递归求全排列,回顾回顾

class Permutations:
def perm(self, num, li, start, end):
s = []
if start == end:
for i in num:
s.append(i)
li.append(s)
else:
for i in range(start, end):
num[start], num[i] = num[i], num[start]
self.perm(num, li, start + 1, end)
num[start], num[i] = num[i], num[start] # @param num, a list of integer
# @return a list of lists of integers def permute(self, num):
li = []
if len(num) == 0:
return []
if len(num) == 1:
return [num]
self.perm(num, li, 0, len(num))
return li pe = Permutations()
pe.permute([3, 2, 1])