[LeetCode]#1299. Replace Elements with Greatest Element on Right Side

Environment: Python 3.7

Key technique: append

Given an array arr, replace every element in that array with the greatest element among the elements to its right, and replace the last element with -1.

After doing so, return the array.

Example 1:

Input: arr = [17,18,5,4,6,1]
Output: [18,6,6,6,1,-1]

Constraints:

• 1 <= arr.length <= 10^4
• 1 <= arr[i] <= 10^5

Analysis:

As below, find right side maximum number and add it to ans list. We can get answer when the searching list is finish.

Solution:

class Solution:
    def replaceElements(self, arr):
        l=len(arr)
        ans=[]
        for i in range(l-1):
 
            arr_r=max(arr[i+1:])
            ans.append(arr_r)
        ans.append(-1)
        return ans

Submitted result: