题目描述

blablabla

样例

blablabla

算法1

(二分法) $O(logn)$

blablabla

时间复杂度分析：blablabla

C++ 代码

class Solution {
public:
    int getNumberSameAsIndex(vector<int>& nums) {
        int n = nums.size();
        int l = 0, r = n-1;
        while(l <= r){
        int mid = (l+r)/2;
        if (nums[mid] == mid) return mid;
        else if (nums[mid] < mid ) l = mid + 1;
        else r = mid - 1;   
        }
        return -1;
    }
};