题目描述

blablabla

C++ 代码

class Solution {
public:
    int getMissingNumber(vector<int>& nums) {
        if (nums.empty()) return 0;
        int l = 0, r =  nums.size() - 1 ;
        if (nums[0] != 0) return 0;
        while(l < r) {
            int mid = l + r + 1>> 1;
            if (nums[mid] == mid) l = mid;
            else r = mid - 1;
        }
        return l + 1;
    }
};