pwc259 solution in go

1 files changed, 90 insertions, 0 deletions

diff --git a/challenge-259/pokgopun/go/ch-1.go b/challenge-259/pokgopun/go/ch-1.go
index ceec77ce84..c013e96ffa 100644
--- a/challenge-259/pokgopun/go/ch-1.go
+++ b/challenge-259/pokgopun/go/ch-1.go
@@ -32,3 +32,93 @@ Output: '2018-07-03'
 Task 2: Line Parser
 #*/
 //# solution by pokgopun@gmail.com
+
+package main
+
+import (
+	"io"
+	"log"
+	"os"
+	"slices"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+const datePttrn = "2006-01-02"
+
+// logic is similar to python version
+func bankingDayOffset(startDate string, offset uint, bankHolidays []string) string {
+	dstart, err := time.Parse(datePttrn, startDate)
+	if err != nil {
+		log.Fatal("invalid date string")
+	}
+	switch dstart.Weekday() { // skip back to Friday if start at weekend
+	case time.Saturday:
+		dstart = dstart.AddDate(0, 0, -1)
+	case time.Sunday:
+		dstart = dstart.AddDate(0, 0, -2)
+	}
+	days := 7*(int(offset)/5) + int(offset)%5    // convert workday offset to everyday offset => 7 days * weekCount (i.e. int(offset)/5) + partial week offset
+	if int(dstart.Weekday())+int(offset)%5 > 5 { // skip weekend if partial week offset int(offset)%5 move dstart beyond current weekday
+		days += 2
+	}
+	dend := dstart.AddDate(0, 0, days)
+	for _, hol := range newHolidays(bankHolidays) {
+		if dstart.Before(hol) && !dend.Before(hol) { // move forward with holidays one by one
+			dend = dend.AddDate(0, 0, 1)
+			if dend.Weekday() > time.Friday { // skip to next monday if such move hit Saturday
+				dend = dend.AddDate(0, 0, 2)
+			}
+		}
+	}
+	return dend.Format(datePttrn)
+}
+
+type holidays []time.Time
+
+// newHolidays silently filter out invalid and duplicated date strings and weekend, dates will be sorted ascendingly as well
+func newHolidays(dateStrs []string) holidays {
+	var hols holidays
+	m := make(map[time.Time]struct{})
+	slices.Sort(dateStrs)
+	for _, dateStr := range dateStrs {
+		date, err := time.Parse(datePttrn, dateStr)
+		if err == nil {
+			switch date.Weekday() {
+			case time.Saturday, time.Sunday:
+				continue
+			}
+			_, ok := m[date]
+			if !ok {
+				m[date] = struct{}{}
+				hols = append(hols, date)
+			}
+		}
+	}
+	return hols
+}
+
+func main() {
+	for _, data := range []struct {
+		output, start string
+		offset        uint
+		holidays      []string
+	}{
+		{"2018-07-04", "2018-06-28", 3, []string{"2018-07-03"}},
+		{"2018-07-03", "2018-06-28", 3, []string{}},
+		{"2018-07-05", "2018-06-28", 3, []string{"2018-07-02", "2018-07-03"}},
+		{"2018-07-05", "2018-06-28", 3, []string{"2018-07-06", "2018-07-03", "2018-07-02"}},
+		{"2018-07-06", "2018-06-28", 3, []string{"2018-07-02", "2018-07-03", "2018-07-05"}},
+		{"2018-07-06", "2018-06-28", 3, []string{"2018-07-02", "2018-07-03", "2018-07-05", "2024-03-05"}},
+		{"2018-07-06", "2018-06-28", 3, []string{"2018-07-02", "2018-07-03", "2018-07-05", "1979-07-09"}},
+		{"2018-07-13", "2018-06-28", 8, []string{"2018-07-02", "2018-07-03", "2018-07-05", "1979-07-09"}},
+		{"2018-07-16", "2018-06-28", 9, []string{"2018-07-02", "2018-07-03", "2018-07-05", "1979-07-09"}},
+		{"2018-07-23", "2018-06-28", 14, []string{"2018-07-02", "2018-07-03", "2018-07-05", "1979-07-09"}},
+		{"2018-07-25", "2018-06-28", 14, []string{"2018-07-02", "2018-07-03", "2018-07-05", "2018-07-11", "2018-07-18"}},
+		{"2018-07-05", "2018-06-29", 3, []string{"2018-07-03"}},
+		{"2018-07-05", "2018-06-30", 3, []string{"2018-07-03"}},
+	} {
+		io.WriteString(os.Stdout, cmp.Diff(bankingDayOffset(data.start, data.offset, data.holidays), data.output)) // blank if ok, otherwise show the differences
+	}
+}