algorithm/leetcode-master
1
0
Fork 0
mirror of https://github.com/youngyangyang04/leetcode-master.git synced 2025-07-08 08:50:15 +08:00
Code Issues Packages Projects Releases Wiki Activity

Update 0018.四数之和.md

Browse Source
This commit is contained in:
jianghongcheng
2023-05-05 21:35:49 -05:00
committed by GitHub
parent 2ddbe7f340
commit a5bb942c95
1 changed files with 29 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
problems/0018.四数之和.md
View File

@ -207,35 +207,40 @@ class Solution {
``` ```
Python： Python：
(版本一) 双指针
```python ```python
# 双指针法 def fourSum(self, nums: List[int], target: int) -> List[List[int]]:
class Solution: result = []
def fourSum(self, nums: List[int], target: int) -> List[List[int]]:
nums.sort() nums.sort()
n = len(nums) for k in range(len(nums)):
res = [] if nums[k] > target and nums[k] >= 0:
for i in range(n): break
if i > 0 and nums[i] == nums[i - 1]: continue # 对nums[i]去重 if k > 0 and nums[k] == nums[k-1]:
for k in range(i+1, n): continue
if k > i + 1 and nums[k] == nums[k-1]: continue # 对nums[k]去重 for i in range(k+1, len(nums)):
p = k + 1 if nums[k] + nums[i] > target and nums[k] + nums[i] >= 0:
q = n - 1 break
if i > k+1 and nums[i] == nums[i-1]:
while p < q: continue
if nums[i] + nums[k] + nums[p] + nums[q] > target: q -= 1 left, right = i+1, len(nums)-1
elif nums[i] + nums[k] + nums[p] + nums[q] < target: p += 1 while right > left:
if nums[k] + nums[i] + nums[left] + nums[right] > target:
right -= 1
elif nums[k] + nums[i] + nums[left] + nums[right] < target:
left += 1
else: else:
res.append([nums[i], nums[k], nums[p], nums[q]]) result.append([nums[k], nums[i], nums[left], nums[right]])
# 对nums[p]和nums[q]去重 while right > left and nums[right] == nums[right-1]:
while p < q and nums[p] == nums[p + 1]: p += 1 right -= 1
while p < q and nums[q] == nums[q - 1]: q -= 1 while right > left and nums[left] == nums[left+1]:
p += 1 left += 1
q -= 1 right -= 1
return res left += 1
return result
``` ```
(版本二) 使用字典
```python ```python
# 哈希表法
class Solution(object): class Solution(object):
def fourSum(self, nums, target): def fourSum(self, nums, target):
""" """