[Algorithm] 12 week(3.28 ~ 4.03) 1/3

852. Peak Index in a Mountain Array

var peakIndexInMountainArray = function(arr) {
    let result = 0;
    
    for(let i = 1; i < arr.length; i++){
        if(arr[i - 1] < arr[i] && arr[i] > arr[i + 1]){
            result = i;
        }
    }
    
    return result;
};