Given an array of integers arr. Return the number of sub-arrays with odd sum.
As the answer may grow large, the answer must be computed modulo 10^9 + 7.
Example 1:
Input: arr = [1,3,5] Output: 4 Explanation: All sub-arrays are [[1],[1,3],[1,3,5],[3],[3,5],[5]] All sub-arrays sum are [1,4,9,3,8,5]. Odd sums are [1,9,3,5] so the answer is 4.
Example 2:
Input: arr = [2,4,6] Output: 0 Explanation: All sub-arrays are [[2],[2,4],[2,4,6],[4],[4,6],[6]] All sub-arrays sum are [2,6,12,4,10,6]. All sub-arrays have even sum and the answer is 0.
Example 3:
Input: arr = [1,2,3,4,5,6,7] Output: 16
Example 4:
Input: arr = [100,100,99,99] Output: 4
Example 5:
Input: arr = [7] Output: 1
Constraints:
1 <= arr.length <= 10^51 <= arr[i] <= 100