package main

import "fmt"

func main() {
	fmt.Println(subarraySum([]int{1, 2, 1, 2, 1}, 3))
}

func subarraySum(nums []int, k int) int {
	result := 0
	hash := make(map[int]int)
	value := 0
	hash[0] = 1
	for i := range nums {
		value += nums[i]
		if v, ok := hash[value-k]; ok {
			result += v
		}
		hash[value]++
	}

	return result
}

//func subarraySum(nums []int, k int) int {
//	slow := 0
//	result := 0
//	for slow < len(nums) {
//		value := 0
//		fmt.Println("1")
//		for fast := slow; fast < len(nums); fast++ {
//			value += nums[fast]
//			if value == k {
//				result += 1
//			}
//		}
//		slow++
//	}
//	return result
//}