题目：原题链接（中等）
标签：数学、回溯算法
解法 | 时间复杂度 | 空间复杂度 | 执行用时 |
Ans 1 (Python) | O ( 2 l o g N ) | O ( 2 l o g N ) | 812ms (31.34%) |
Ans 2 (Python) | |||
Ans 3 (Python) |
解法一：
class Solution:
def __init__(self):
self.ans = set()
def getFactors(self, n: int) -> List[List[int]]:
if n == 1:
return []
# 因子分解
factor = []
now = 2
while now <= n:
while n % now == 0:
factor.append(now)
n //= now
now += 1
if len(factor) == 1:
return []
self.dfs(tuple(sorted(factor)))
return list(list(elem) for elem in self.ans)
def dfs(self, factor):
if len(factor) > 1:
self.ans.add(factor)
visited = set()
for f1, f2 in itertools.combinations(factor, 2):
f1, f2 = min(f1, f2), max(f1, f2)
if (f1, f2) not in visited:
visited.add((f1, f2))
new_factor = list(factor)
new_factor.remove(f1)
new_factor.remove(f2)
new_factor.append(f1 * f2)
self.dfs(tuple(sorted(new_factor)))
