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Update 回溯算法去重问题的另一种写法.md
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@ -356,76 +356,80 @@ Python:
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```python
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class Solution:
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def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
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res = []
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nums.sort()
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def backtracking(start, path):
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res.append(path)
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uset = set()
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for i in range(start, len(nums)):
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if nums[i] not in uset:
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backtracking(i + 1, path + [nums[i]])
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uset.add(nums[i])
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def subsetsWithDup(self, nums):
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nums.sort() # 去重需要排序
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result = []
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self.backtracking(nums, 0, [], result)
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return result
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def backtracking(self, nums, startIndex, path, result):
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result.append(path[:])
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used = set()
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for i in range(startIndex, len(nums)):
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if nums[i] in used:
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continue
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used.add(nums[i])
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path.append(nums[i])
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self.backtracking(nums, i + 1, path, result)
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path.pop()
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backtracking(0, [])
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return res
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```
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**40. 组合总和 II**
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```python
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class Solution:
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def combinationSum2(self, candidates: List[int], target: int) -> List[List[int]]:
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res = []
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def combinationSum2(self, candidates, target):
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candidates.sort()
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result = []
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self.backtracking(candidates, target, 0, 0, [], result)
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return result
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def backtracking(start, path):
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if sum(path) == target:
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res.append(path)
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elif sum(path) < target:
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used = set()
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for i in range(start, len(candidates)):
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if candidates[i] in used:
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continue
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else:
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used.add(candidates[i])
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backtracking(i + 1, path + [candidates[i]])
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backtracking(0, [])
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def backtracking(self, candidates, target, sum, startIndex, path, result):
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if sum == target:
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result.append(path[:])
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return
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used = set()
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for i in range(startIndex, len(candidates)):
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if sum + candidates[i] > target:
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break
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if candidates[i] in used:
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continue
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used.add(candidates[i])
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sum += candidates[i]
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path.append(candidates[i])
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self.backtracking(candidates, target, sum, i + 1, path, result)
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sum -= candidates[i]
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path.pop()
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return res
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```
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**47. 全排列 II**
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```python
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class Solution:
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def permuteUnique(self, nums: List[int]) -> List[List[int]]:
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path = []
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res = []
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used = [False]*len(nums)
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def permuteUnique(self, nums):
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nums.sort() # 排序
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result = []
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self.backtracking(nums, [False] * len(nums), [], result)
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return result
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def backtracking():
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if len(path) == len(nums):
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res.append(path.copy())
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deduplicate = set()
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for i, num in enumerate(nums):
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if used[i] == True:
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continue
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if num in deduplicate:
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continue
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def backtracking(self, nums, used, path, result):
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if len(path) == len(nums):
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result.append(path[:])
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return
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used_set = set()
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for i in range(len(nums)):
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if nums[i] in used_set:
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continue
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if not used[i]:
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used_set.add(nums[i])
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used[i] = True
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path.append(nums[i])
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backtracking()
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used[i] = False
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self.backtracking(nums, used, path, result)
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path.pop()
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deduplicate.add(num)
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backtracking()
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used[i] = False
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return res
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```
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JavaScript:
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