剑指 Offer 53 - II. 0～n-1中缺失的数字

二分

class Solution {
    public int missingNumber(int[] nums) {
        int l = 0, r = nums.length - 1;
        while(l < r){
            int mid = l + r >> 1;
            if(nums[mid] == mid) l = mid + 1;
            else r = mid;
        }
        return nums[l] == l ? l + 1 : l;
    }
}