LeetCode#1588. Sum of All Odd Length Subarrays

1588. Sum of All Odd Length Subarrays

Given an array of positive integers arr, calculate the sum of all possible odd-length subarrays.

A subarray is a contiguous subsequence of the array.

Return the sum of all odd-length subarrays of arr.

Example 1:

Input: arr = [1,4,2,5,3]
Output: 58
Explanation: The odd-length subarrays of arr and their sums are:
[1] = 1
[4] = 4
[2] = 2
[5] = 5
[3] = 3
[1,4,2] = 7
[4,2,5] = 11
[2,5,3] = 10
[1,4,2,5,3] = 15
If we add all these together we get 1 + 4 + 2 + 5 + 3 + 7 + 11 + 10 + 15 = 58

Example 2:

Input: arr = [1,2]
Output: 3
Explanation: There are only 2 subarrays of odd length, [1] and [2]. Their sum is 3.

Example 3:

Input: arr = [10,11,12]
Output: 66

Constraints:

• 1 <= arr.length <= 100
• 1 <= arr[i] <= 1000

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暴力🤣

class Solution {
    public int sumOddLengthSubarrays(int[] arr) {
        int length=arr.length;
        int n=1;
        int sum=0;
        while(n<=length){
            for(int i=0;i<length;i++){
                if(i+n>length){
                    break;
                }else{
                    for(int j=0;j<n;j++){
                        sum+=arr[i+j];
                    }
                }
            }
            n+=2;
        }
        return sum;
    }
}