3 files changed, 82 insertions, 0 deletions
diff --git a/challenge-013/pokgopun/README b/challenge-013/pokgopun/README
new file mode 100644
index 0000000000..33dfd303a4
--- /dev/null
+++ b/challenge-013/pokgopun/README
@@ -0,0 +1 @@
+Solution by PokGoPun
diff --git a/challenge-013/pokgopun/go/ch-1.go b/challenge-013/pokgopun/go/ch-1.go
new file mode 100644
index 0000000000..d7e704436e
--- /dev/null
+++ b/challenge-013/pokgopun/go/ch-1.go
@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	fmt.Println(newLastWeekdayOfMonth(time.Friday, 2019))
+}
+func monthdayCount(y int) (r [12]int) {
+	r = [12]int{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
+	if y%4 == 0 {
+		r[time.February]++
+	}
+	return r
+}
+
+type lastWeekdayOfMonth [12]time.Time
+
+func (lwdom lastWeekdayOfMonth) String() (r string) {
+	for _, t := range lwdom {
+		r += fmt.Sprintln(t.Format("2006/01/02"))
+	}
+	return r
+}
+func newLastWeekdayOfMonth(wd time.Weekday, y int) (lwdom lastWeekdayOfMonth) {
+	for i, v := range monthdayCount(y) {
+		// Find offset between the last day of the month and the specified weekday
+		t := time.Date(y, time.Month(i+1), v, 0, 0, 0, 0, time.UTC)
+		o := int(wd - t.Weekday())
+		// The offset is the number of day we need to go back to the latest specified weekday in certain month
+		if o != 0 {
+			// plus sign indicate the offset between specified weekday and the current weekday of the previous week
+			if o > 0 {
+				o -= 7
+			}
+		}
+		lwdom[i] = t.AddDate(0, 0, o)
+	}
+	return lwdom
+}
diff --git a/challenge-013/pokgopun/go/ch-2.go b/challenge-013/pokgopun/go/ch-2.go
new file mode 100644
index 0000000000..7cee43a19a
--- /dev/null
+++ b/challenge-013/pokgopun/go/ch-2.go
@@ -0,0 +1,39 @@
+/*
+ F ( 0 ) = 1   ;   M ( 0 ) = 0
+ F ( n ) = n − M ( F ( n − 1 ) ) , n > 0
+ M ( n ) = n − F ( M ( n − 1 ) ) , n > 0.
+*/
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+func main() {
+	w := bufio.NewWriter(os.Stdout)
+	fmt.Fprintf(w, "| %4s | %4s | %4s |", "n", "F(n)", "M(n)")
+	w.WriteString("\n" + strings.Repeat("-", w.Buffered()) + "\n")
+	var n uint
+	for n <= 20 {
+		fmt.Fprintf(w, "| %4d | %4d | %4d |\n", n, female(n), male(n))
+		n++
+	}
+	w.Flush()
+}
+
+func female(n uint) uint {
+	if n == 0 {
+		return 1
+	}
+	return n - male(female(n-1))
+}
+
+func male(n uint) uint {
+	if n == 0 {
+		return 0
+	}
+	return n - female(male(n-1))
+}