标签：lan desc example ret pointer object blank obj number
https://leetcode.com/problems/3sum/#/description
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.
Note: The solution set must not contain duplicate triplets.
For example, given array S = [-1, 0, 1, 2, -1, -4], A solution set is: [ [-1, 0, 1], [-1, -1, 2] ]
Sol:
class Solution(object): def threeSum(self, nums): """ :type nums: List[int] :rtype: List[List[int]] """ # sort first and then use two pointers to push upon the mid point # skip repeated numbers # Space O(n^2), Time O(1) result = [] if len(nums) < 3: return result sorted(nums) target = 0 for i in range(len(nums) - 1): if i > 0 and nums[i] == nums[i-1]: continue j = i + 1 k = len(nums) - 1 while j < k: if nums[i] + nums[j] + nums[k] < target: j += 1 while nums[j] == nums[j-1] and j < k: j += 1 elif nums[i] + nums[j] +nums[k] > target: k -= 1 while nums[k] == nums[k+1] and j < k: k -= 1 else: result.append([nums[i], nums[j], nums[k]]) j += 1 k -= 1 while nums[j] == nums[j-1] and j < k: j += 1 while nums[k] == nums[k+1] and j < k: k -= 1
标签：lan desc example ret pointer object blank obj number
原文地址：http://www.cnblogs.com/prmlab/p/7113555.html
