package main

func numSubarraysWithSum(nums []int, goal int) (res int) {
	rolingTable := make(map[int]int)
	sum := 0
	for _, v := range nums {
		rolingTable[sum]++
		sum += v
		if va, ok := rolingTable[sum-goal]; ok {
			res += va
		}
	}
	return res
}