Java simple solution
\'\'\'\nclass Solution {\n    public List> fourSum(int[] nums, int target) {\n        List> result=new ArrayList<>();\n        if(nums==null || nums.length<4){\
\'\'\'\nclass Solution {\n    public List<List<Integer>> fourSum(int[] nums, int target) {\n        List<List<Integer>> result=new ArrayList<>();\n        if(nums==null || nums.length<4){\n            return result;\n        }\n        Arrays.sort(nums);\n        int n=nums.length;\n        \n        for(int i=0;i<n-3;i++){\n            for(int j=i+1;j<n-2;j++){\n                int low=j+1;\n                int high=n-1;\n                \n                while(low<high){\n                    int sum=nums[i]+nums[j]+nums[low]+nums[high];\n                    if(sum==target){\n                        List<Integer>list=new ArrayList<>();\n                        list.add(nums[i]);\n                        list.add(nums[j]);\n                        list.add(nums[low]);\n                        list.add(nums[high]);\n                \n                \n                if(result.contains(list)==false){\n                    result.add(list);\n                }\n                low++;\n                high--;\n                    }\n             else if(sum<target){\n                    low++;\n                }\n                else{\n                    high--;\n                }\n                }\n            }\n        }\n        return result;\n                \n    }\n}\n\'\'\'
['Java']