leetcode/lcci/17.04.Missing Number/Solution.java

class Solution {
    public int missingNumber(int[] nums) {
        Arrays.sort(nums);
        int n = nums.length;
        for (int i = 0; i < n; ++i) {
            if (i != nums[i]) {
                return i;
            }
        }
        return n;
    }
}