An array is in ascending order and then descending in order to find the maximum value with the optimal time complexity. For example, [1, 2, 2, 2, 2, 2, 2, 3, 1]

an array is in ascending order and then descending in order to find the maximum value. For example, [1, 2, 2, 2, 2, 2, 2, 3, 1], using the optimal time complexity, the algorithm achieves the maximum value 3

.
Java cPP
Sep.30,2021 
/**
 * 
 * @param arr : 
 * @param low : 
 * @param high: 
 * @return    : 
 */
public static int getMax(int[] arr, int low, int high) {
   
    while (low < high) 
    {
        int mid = low + ((high - low) >> 1);
        if (arr[mid] > arr[mid + 1]) {
            high = mid;
        } 
        else if (arr[mid] < arr[mid + 1])  {
            low = mid + 1;
        }
        else  //arr[mid]arr[mid+1]
        {                
            if (mid-1 >= low) //  [low~high]
            {
                if(arr[mid-1] > arr[mid])
                {
                    high = mid-1;
                }
                else if(arr[mid-1] < arr[mid])
                {
                    low = mid+1;
                }
                else //arr[mid-1]  arr[mid]  arr[mid-1]arr[mid],arr[mid+1]  
                    //midmidmidmid
                    //
                {
                    int one = getMax(arr, low, mid-1);
                    int two = getMax(arr, mid+1, high);
                    
                    return one > two ? one : two;
                }
            }
            else { // mid-1 < low  midlowarr[low] == arr[high]
                return arr[low];
            }
        }
    }
    
    return arr[low];
}

= update
Recursion and array copy are removed, and the return value of the function is changed to index to facilitate the handling of empty arrays 

  
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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1e36026-58905.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e36026-58905.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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