163.Missing Ranges

    /*
     * 163.Missing Ranges
     * 2016-6-3 by Mingyang
     * 自己的代码未贴出来。原理就是只要这个是count发的下一个，就只加count，
     * 否则就把count加了以后再加自己
     */
     public List<String> findMissingRanges(int[] A, int lower, int upper) {
            List<String> result = new ArrayList<String>();
            int pre = lower - 1;
            for(int i = 0 ; i <= A.length  ; i++){
                int after = i == A.length ? upper + 1 : A[i]; 
                if(pre + 2 == after){
                    result.add(String.valueOf(pre + 1));
                }else if(pre + 2 < after){
                    result.add(String.valueOf(pre + 1) + "->" + String.valueOf(after - 1));
                }
                pre = after;
            }
            return result;
        }