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:
- Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c)
- 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)
代码如下:(超时)
1 public class Solution { 2 public List<List<Integer>> threeSum(int[] nums) { 3 List<List<Integer>> list1=new ArrayList<>(); 4 List<Integer> list=new ArrayList<>(); 5 Map<List<Integer>,List<Integer>> map=new HashMap<>(); 6 int a=0; 7 8 Arrays.sort(nums); 9 10 for(int i=0;i<=nums.length-3;i++)11 {12 if(nums[i]<=0)13 {14 list.add(nums[i]);15 a=nums[i]*(-1);16 }17 else break;18 for(int j=i+1;j<=nums.length-2;j++)19 {20 if(nums[j]<=a)21 {22 list.add(nums[j]);23 a=a-nums[j];24 for(int k=j+1;k<=nums.length-1;k++)25 {26 if(nums[k]>a)27 break; 28 else if(nums[k]==a)29 {30 list.add(nums[k]);31 if(!map.containsKey(list))32 {33 map.put(list, list);34 list1.add(list);35 }36 break;37 }38 39 }40 }41 else break;42 list=new ArrayList<>();43 list.add(nums[i]);44 a=nums[i]*(-1);45 }46 list=new ArrayList<>();47 }48 49 return list1;50 }51 }
原标题:15. 3Sum
关键词: