[LeetCode]3Sum

    public List<List<Integer>> threeSum(int[] num) {
        List<List<Integer>> rs = new LinkedList<List<Integer>>();
        if(num == null || num.length < 3) return rs;//不能返回null
        Arrays.sort(num);
        System.out.println();
        //a + b + c ==0
        final int target = 0;
        for(int a =0; a < num.length-2;){//先固定第一个数字
            if(num[a] > target) return rs;
            int b = a + 1, c = num.length - 1;
            while (b < c){//对后面两个数据进行调整
                int sum = num[a] + num[b] + num[c];
                if(sum == target){
                    List<Integer> r = new LinkedList<Integer>();
                    r.add(num[a]);
                    r.add(num[b]);
                    r.add(num[c]);
                    rs.add(r);
                    b++;
                    while (b<c && num[b] == num[b-1])b++;//防止重复数据
                    c--;
                    while (b<c && num[c + 1] == num[c])c--;

                }else if(sum > target){
                    c--;
                }else {
                    b++;
                }
            }
            a ++;
            while (a< num.length -2 && num[a-1] == num[a]) a++;//防止重复
        }
        return rs;
    }

[LeetCode]3Sum

原文：http://blog.csdn.net/youmengjiuzhuiba/article/details/44810745