15. 3Sum

15. 3Sum

class Solution {
    public List<List<Integer>> threeSum(int[] nums) {
    	List<List<Integer>> result=new ArrayList<>();
    	Arrays.sort(nums);
   	 	for(int i=0;i<nums.length;i++){
      		if(i>0&&nums[i]==nums[i-1]){
        		continue;
      		}
      	int sum=nums[i],start=i+1,end=nums.length-1;
      	while(start<end){
        	if(nums[start]+nums[end]==-sum){
          		List<Integer> temp=new ArrayList<>();
          		temp.add(sum);
          		temp.add(nums[start]);
          		temp.add(nums[end]);
          		result.add(temp);
          		while (start<end&&nums[start+1]==nums[start]){
            		start++;
          		}
          		start++;
          		while (start<end&&nums[end]==nums[end-1]){
            		end--;
          		}
          		end--;
        	}else if(nums[start]+nums[end]>-sum){
          		end--;
        	}else {
          		start++;
        	}
      	}
    }
    return result;
    }
}