829. 連續整數求和-leetcode

題目：給定一個正整數 N，試求有多少組連續正整數知足全部數字之和爲 N?

示例 1:

輸入: 5
輸出: 2

解釋: 5 = 5 = 2 + 3，共有兩組連續整數([5],[2,3])求和後爲 5。

示例 2:

輸入: 9
輸出: 3

解釋: 9 = 9 = 4 + 5 = 2 + 3 + 4
示例 3:

輸入: 15
輸出: 4

解釋: 15 = 15 = 8 + 7 = 4 + 5 + 6 = 1 + 2 + 3 + 4 + 5

說明: 1 <= N <= 10 ^ 9

/* 
N = (p+0)+(p+1)+(p+2)+...+(p+i-1)

  = p*i +i*(i-1)/2
  
  ===>
        2*N = (p*2+i-1)*i (p,i都是正整數)
 */ 

import "math"
func consecutiveNumbersSum(N int) int {
    var sum = 0
    dataChan := make(chan int, 10)
    outChan := make(chan byte, 10)

go func() {
    defer close(dataChan)
    for i := 1; float64(i) <= math.Sqrt(float64(2*N)); i++ {
        if (2*N)%i == 0 {
            dataChan <- i
        }
    }
}()

go func() {
    for {
        if i, ok := <-dataChan; !ok {
            close(outChan)
            return
        } else {
            p := (2*N)/i - i - 1
            if p >= 0 && (p&1 == 0) {
                // fmt.Println("offset,i", p/2, i)
                outChan <- 0
            }
        }
    }

}()

for {
    if _, ok := <-outChan; ok {
        sum++
    } else {
        break
    }
}
return sum
}