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Update 0491.递增子序列.md

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jianghongcheng
2023-05-27 19:21:17 -05:00
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problems/0491.递增子序列.md
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@ -272,23 +272,24 @@ class Solution {
class Solution: class Solution:
def findSubsequences(self, nums): def findSubsequences(self, nums):
result = [] result = []
self.backtracking(nums, 0, [], result) path = []
self.backtracking(nums, 0, path, result)
return result return result
def backtracking(self, nums, startIndex, path, result): def backtracking(self, nums, startIndex, path, result):
if len(path) > 1: if len(path) > 1:
result.append(path[:]) # 将当前路径的副本加入结果集 result.append(path[:]) # 注意要使用切片将当前路径的副本加入结果集
# 注意这里不要加return，要取树上的节点
used = set() # 使用集合来进行去重操作 uset = set() # 使用集合对本层元素进行去重
for i in range(startIndex, len(nums)): for i in range(startIndex, len(nums)):
if path and nums[i] < path[-1]: if (path and nums[i] < path[-1]) or nums[i] in uset:
continue # 如果当前元素小于上一个元素，则跳过当前元素 continue
if nums[i] in used: uset.add(nums[i]) # 记录这个元素在本层用过了，本层后面不能再用了
continue # 如果当前元素已经使用过，则跳过当前元素 path.append(nums[i])
self.backtracking(nums, i + 1, path, result)
used.add(nums[i]) # 标记当前元素已经使用过 path.pop()
self.backtracking(nums, i + 1, path + [nums[i]], result)
``` ```
回溯 利用哈希表去重 回溯 利用哈希表去重
@ -314,6 +315,7 @@ class Solution:
self.backtracking(nums, i + 1, path, result) self.backtracking(nums, i + 1, path, result)
path.pop() path.pop()
``` ```
### Go ### Go