Howard的程式筆記

1299. Replace Elements with Greatest Element on Right Side (替換右邊最大值 最後值為-1)

分類於

題目

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

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Input: arr = [17,18,5,4,6,1]
Output: [18,6,6,6,1,-1]
Explanation: 
- index 0 --> the greatest element to the right of index 0 is index 1 (18).
- index 1 --> the greatest element to the right of index 1 is index 4 (6).
- index 2 --> the greatest element to the right of index 2 is index 4 (6).
- index 3 --> the greatest element to the right of index 3 is index 4 (6).
- index 4 --> the greatest element to the right of index 4 is index 5 (1).
- index 5 --> there are no elements to the right of index 5, so we put -1.

Example 2

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Input: arr = [400]
Output: [-1]
Explanation: There are no elements to the right of index 0.

Constraints:

  • 1 <= arr.length <= 104
  • 1 <= arr[i] <= 105

我的解題

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class Solution {
    public int[] replaceElements(int[] arr) {
        
        if(arr.length <= 1) arr[arr.length-1]= -1;
        
        for(int i=arr.length-2;i>=0;i--){
            int temp = arr[i];
            arr[i]=arr[arr.length-1];
            if(arr[arr.length-1] < temp){
                arr[arr.length-1]=temp;
            }
        }
        
        arr[arr.length-1]= -1;
        
        return arr;
    }
}