[leetcode]Peak Index in a Mountain Array

유의할점

인덱스-1로 하면 안됨.

풀이

코드

C++

class Solution {
public:
    int peakIndexInMountainArray(vector<int>& arr) {
        int begin = 0;
        int end = arr.size()-1;
        while(begin < end){
            int mid = (begin + end) / 2;
            
            if(arr[mid]<arr[mid+1]){
                begin = mid+1;
            }else{
                end = mid;
            }
        }
        return begin;
    }
};