peakelement_mountainarray.cpp

#include <iostream>
#include <vector>
using namespace std;

class Solution {
public:
    int peakIndexInMountainArray(vector<int>& arr) {
        int s = 0;
        int e = arr.size()-1;

        int mid = s + (e-s)/2;

        while(s < e){
            if(arr[mid] < arr[mid+1]){
                s = mid + 1;
            }
            else{
                e = mid;
            }
            mid = s + (e-s)/2;
        }
        return s;
    }
};