LeetCode_3Sum.java

class Solution {
    public List<List<Integer>> threeSum(int[] nums) {
        Arrays.sort(nums);
        List<List<Integer>> list = new LinkedList<>();
        for(int i=0 ; i<nums.length-2 ; i++){
            if(i==0 || (i>0&&nums[i]!=nums[i-1])){
                int lo = i+1, hi = nums.length-1, sum=0-nums[i];
                while(lo<hi){
                    if(nums[lo]+nums[hi]==sum){
                        list.add(Arrays.asList(nums[i],nums[lo],nums[hi]));
                        while(lo<hi&&nums[lo]==nums[lo+1]) lo++;
                        while(lo<hi&&nums[hi]==nums[hi-1]) hi--;
                        hi--;lo++;
                    }else if(nums[lo]+nums[hi]<sum){
                        lo++;
                    }else{
                        hi--;
                    }
                }
            }
        }
        return list;
    }
}