来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/subsets
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
"""
from typing import List
import validator
class Solution:
def subsets(self, nums: List[int]) -> List[List[int]]:
def search(cur_nums: List[int], start_index: int, total_count: int):
if len(cur_nums) == total_count:
result.append(cur_nums[:])
return
for i in range(start_index, len(nums)):
cur_nums.append(nums[i])
search(cur_nums, i + 1, total_count)
cur_nums.remove(nums[i])
result = []
for n in range(len(nums) + 1):
search([], 0, n)
return result
if __name__ == '__main__':
validator.validate_without_order(Solution().subsets(
[1, 2, 3]), [[1], [3], [2], [1, 2, 3], [1, 3], [2, 3], [1, 2], []])
class Solution:
def combinationSum3(self, k: int, n: int) -> List[List[int]]:
def backtracking(cur_nums=[], leaving=n, cur_idx=1):
len_cur = len(cur_nums)
if len_cur == k:
if leaving == 0:
result.append(cur_nums)
return
for i in range(cur_idx, 10):
if (leaving - i < 0) or (10 - i < k - len_cur) or (leaving > leaving_sum[10 - k + len_cur]):
# condition1: leaving比i小，后续任意数字加上都会超
# condition2: 剩余数字全选上，总数量仍然达不到预期数量n;
# condition3: 剩余数字总和 > sum(i,9),即 全部加上也达不到leaving
break
backtracking(cur_nums + [i], leaving - i, i + 1)
leaving_sum = [0, 45, 44, 42, 39, 35, 30, 24, 17, 9]
result = []
backtracking()
return result
if __name__ == '__main__':
validator.validate_without_order(Solution().combinationSum3(3, 7), [[1, 2, 4]])
validator.validate_without_order(Solution().combinationSum3(3, 9), [[1, 2, 6], [1, 3, 5], [2, 3, 4]])
validator.validate_without_order(Solution().combinationSum3(3, 100), [])
validator.validate_without_order(Solution().combinationSum3(9, 46), [])
validator.validate_without_order(Solution().combinationSum3(2, 6), [[1, 5], [2, 4]])
链接：https://leetcode-cn.com/problems/permutations
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
"""
from typing import List
import validator
class Solution:
def permute(self, nums: List[int]) -> List[List[int]]:
def backtracking(leaving_nums: List[int], cur_nums=list()):
if len(leaving_nums) == 0:
result.append(cur_nums[:])
return
for num in leaving_nums:
cur_nums.append(num)
ori_index = leaving_nums.index(num)
leaving_nums.remove(num)
backtracking(leaving_nums, cur_nums)
leaving_nums.insert(ori_index, num)
cur_nums.remove(num)
result = []
backtracking(nums)
return result
if __name__ == '__main__':
validator.validate_without_order(Solution().permute([1, 2, 3]),
[[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]])
if leaving == 0:
if nums not in result:
result.append(nums)
return
for i in range(cur_idx, len(candidates)):
if leaving < candidates[i]:
break
if i > cur_idx and candidates[i] == candidates[i - 1]:
continue
backtracking(nums + [candidates[i]], leaving - candidates[i],
i + 1)
result = list()
candidates.sort()
backtracking()
return result
if __name__ == '__main__':
validator.validate_without_order(
Solution().combinationSum2([10, 1, 2, 7, 6, 1, 5], 8),
[[1, 7], [1, 2, 5], [2, 6], [1, 1, 6]])
validator.validate_without_order(
Solution().combinationSum2([2, 5, 2, 1, 2], 5), [[1, 2, 2], [5]])
print(Solution().combinationSum2([
29, 19, 14, 33, 11, 5, 9, 23, 23, 33, 12, 9, 25, 25, 12, 21, 14, 11,
20, 30, 17, 19, 5, 6, 6, 5, 5, 11, 12, 25, 31, 28, 31, 33, 27, 7, 33,
31, 17, 13, 21, 24, 17, 12, 6, 16, 20, 16, 22, 5
], 28))
class Solution:
def intersect(self, nums1: List[int], nums2: List[int]) -> List[int]:
nums1_count = collections.Counter(nums1)
result = []
for i in range(len(nums2)):
if nums1_count.get(nums2[i], 0) > 0:
result.append(nums2[i])
nums1_count[nums2[i]] -= 1
return result
def intersectV2(self, nums1: List[int], nums2: List[int]) -> List[int]:
if len(nums1) > len(nums2):
return self.intersect(nums2, nums1)
result = []
for i in range(len(nums1)):
if not nums2:
break
if nums1[i] in nums2:
result.append(nums1[i])
nums2.remove(nums1[i])
return result
if __name__ == '__main__':
validate_without_order(Solution().intersect([4, 9, 5], [9, 4, 9, 8, 4]),
[4, 9])
validate_without_order(Solution().intersect([1, 2, 2, 1], [2, 2]), [2, 2])
for len1 in range(3):
for len2 in range(3):
for len3 in range(3):
len4 = len_s - len1 - len2 - len3 - 3
if len4 < 1 or len4 > 3:
continue
part1, part2, part3, part4 = s[:len1 + 1], s[len1 + 1: len1 + len2 + 2], \
s[len1 + len2 + 2: len1 + len2 + len3 + 3], s[len1 + len2 + len3 + 3:]
if (len(part1) > 1 and part1[0] == '0') or (len(part2) > 1 and part2[0] == '0') \
or (len(part3) > 1 and part3[0] == '0') or (len(part4) > 1 and part4[0] == '0'):
continue
if int(part1) <= 255 and int(part2) <= 255 and int(
part3) <= 255 and int(part4) <= 255:
result.append('.'.join([part1, part2, part3, part4]))
return result
if __name__ == '__main__':
validator.validate_without_order(
Solution().restoreIpAddresses("25525511135"),
["255.255.11.135", "255.255.111.35"])
validator.validate_without_order(Solution().restoreIpAddresses("0000"),
["0.0.0.0"])
validator.validate_without_order(Solution().restoreIpAddresses("1111"),
["1.1.1.1"])
validator.validate_without_order(Solution().restoreIpAddresses("010010"),
["0.10.0.10", "0.100.1.0"])
validator.validate_without_order(
Solution().restoreIpAddresses("101023"),
["1.0.10.23", "1.0.102.3", "10.1.0.23", "10.10.2.3", "101.0.2.3"])