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