3sum

Solution.java

class Solution {
    public List<List<Integer>> threeSum(int[] nums) {

        Set<List<Integer>> combos = new HashSet<List<Integer>>();
        Arrays.sort(nums);
        Map<Integer, Integer> values = new HashMap<Integer,Integer>();
        for(int i = 0; i<nums.length;i++){
            if(values.containsKey(nums[i])){
                values.put(nums[i],values.get(nums[i])+1);
            }else{
                values.put(nums[i],1);
            }
        }

        for(int i = 0 ; i<nums.length-2; i++){

            if(nums[i]<=0){
                for(int j = i+1; j<nums.length-1; j++){

                    if(nums[i]+nums[j]<=0){
                        int keyNeeded = -1*(nums[i]+nums[j]);
                        if(values.containsKey(keyNeeded) ){
                            boolean shouldAdd = false;
                            //now we need to ensure we have enough counts
                            if(keyNeeded==nums[i]||keyNeeded==nums[j]){
                                if(nums[i]==0){
                                    if (values.get(0)>2){
                                        //we're good here
                                        shouldAdd = true;
                                    }
                                }else if(values.get(keyNeeded)>1){
                                    //we're good here
                                    shouldAdd = true;
                                }
                            }else {
                                shouldAdd = true;
                            }
                            if (shouldAdd){
                                List<Integer>
                                    validCombo = Arrays.asList(nums[i],nums[j],keyNeeded);
                                Collections.sort(validCombo);
                                combos.add(validCombo);
                            }
                        }
                    }else{
                        break;
                    }
                }
            }else {
                break;
            }

        }
        List<List<Integer>> list = new ArrayList<List<Integer>>();

        Iterator<List<Integer>> iter = combos.iterator();
        while(iter.hasNext()){
            list.add(iter.next());
        }

        return list;
    }
}