From 1354cf80de7115334f0f499a0f09bdcc020de0cc Mon Sep 17 00:00:00 2001
From: Michael Manring <michael@manring>
Date: Mon, 14 Mar 2022 18:28:20 +0700
Subject: pwc156 solution in GO

---
 challenge-156/pokgopun/go/ch-1.go | 74 +++++++++++++++++++++++++++++++++
 challenge-156/pokgopun/go/ch-2.go | 87 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 161 insertions(+)
 create mode 100644 challenge-156/pokgopun/go/ch-1.go
 create mode 100644 challenge-156/pokgopun/go/ch-2.go

diff --git a/challenge-156/pokgopun/go/ch-1.go b/challenge-156/pokgopun/go/ch-1.go
new file mode 100644
index 0000000000..44adad9f21
--- /dev/null
+++ b/challenge-156/pokgopun/go/ch-1.go
@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+)
+
+func main() {
+	n := getArgInt(10)
+	var (
+		ps string
+		pc int
+	)
+	chk := checkPrime()
+	for i := 1; i < 10000; i++ {
+		sum := sumb(i)
+		//fmt.Println("binary sum of", i, " is", sum)
+		if chk(sum) {
+			ps += fmt.Sprint(i, ", ")
+			pc++
+		}
+		if pc == n {
+			fmt.Println(ps[:len(ps)-2])
+			break
+		}
+	}
+}
+func sumb(i int) (s int) {
+	for j := i; j > 0; j /= 2 {
+		s += j % 2
+	}
+	return s
+}
+func getArgInt(n int) int {
+	if len(os.Args) > 1 {
+		u, err := strconv.ParseUint(os.Args[1], 10, 64)
+		if err != nil {
+			log.Fatal(err)
+		}
+		n = int(u)
+	}
+	return n
+}
+func checkPrime() func(i int) bool {
+	m := map[int]bool{}
+	return func(i int) bool {
+		is, ok := m[i]
+		if ok {
+			return is
+		} else {
+			if isPrime(i) {
+				m[i] = true
+				return true
+			}
+			m[i] = false
+			return false
+		}
+	}
+}
+func isPrime(n int) bool {
+	if n <= 3 {
+		return n > 1
+	} else if n%2 == 0 || n%3 == 0 {
+		return false
+	}
+	for i := 5; i*i <= n; i += 6 {
+		if n%i == 0 || n%(i+2) == 0 {
+			return false
+		}
+	}
+	return true
+}
diff --git a/challenge-156/pokgopun/go/ch-2.go b/challenge-156/pokgopun/go/ch-2.go
new file mode 100644
index 0000000000..b856d58314
--- /dev/null
+++ b/challenge-156/pokgopun/go/ch-2.go
@@ -0,0 +1,87 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+)
+
+func main() {
+	i := getArgInt(12)
+	d := getDivisors(i)
+	sum := 0
+	for _, v := range d {
+		sum += v
+	}
+	var o int
+	ds := []int{}
+	var sums int
+	if sum > i {
+		o = 1
+		for j := 2; j < len(d); j++ {
+			sos := getCombo(j, d)
+			for _, s := range sos {
+				var sum int
+				for _, v := range s {
+					sum += v
+				}
+				if sum == i {
+					o = 0
+					ds = s
+					sums = sum
+					goto done
+				}
+			}
+		}
+	}
+done:
+	fmt.Println("Input: $n =", i)
+	msg := fmt.Sprint("The proper divisors ", d, " sum to ", sum, " which is ")
+	if sum > i {
+		fmt.Print(msg, "greater than $n")
+	} else {
+		fmt.Print(msg, "less than $n\n")
+	}
+	if sums != 0 {
+		fmt.Println(", but its subset", ds, "sums to", sums)
+	} else if o == 1 {
+		fmt.Println(" and none of its subset sums to", i)
+	}
+	fmt.Println("Output:", o)
+}
+func getArgInt(n int) int {
+	if len(os.Args) > 1 {
+		u, err := strconv.ParseUint(os.Args[1], 10, 64)
+		if err != nil {
+			log.Fatal(err)
+		}
+		n = int(u)
+	}
+	return n
+}
+func getDivisors(n int) (d []int) {
+	for i := 1; i <= n/2; i++ {
+		if n%i == 0 {
+			d = append(d, i)
+		}
+	}
+	return d
+}
+func getCombo(n int, e []int) (r [][]int) {
+	c := []int{}
+	cTree(n, e, c, func(s []int) {
+		r = append(r, s)
+	})
+	return r
+}
+func cTree(n int, e []int, c []int, f func(s []int)) {
+	if len(c) == n || len(c)+len(e) == n {
+		s := append(c, e...)
+		f(s[:n])
+	} else {
+		for i := 0; len(c)+len(e)-i >= n; i++ {
+			cTree(n, e[i+1:], append(c, e[i]), f)
+		}
+	}
+}
-- 
cgit