163.缺失的区间

class Solution {
    public List<List<Integer>> findMissingRanges(int[] nums, int lower, int upper) {
        List<List<Integer>> res = new ArrayList<>();
        for(int num : nums){
            if(lower < num){
                res.add(Arrays.asList(lower,num - 1));
            }
            lower = num + 1;   
        }
        if(lower <= upper){
            res.add( Arrays.asList(lower,upper));
        }
        return res;

    }
}