Data commit

Task/Palindrome-dates/Go/palindrome-dates-1.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+    "fmt"
+    "time"
+)
+
+func reverse(s string) string {
+    chars := []rune(s)
+    for i, j := 0, len(chars)-1; i < j; i, j = i+1, j-1 {
+        chars[i], chars[j] = chars[j], chars[i]
+    }
+    return string(chars)
+}
+
+func main() {
+    const (
+        layout  = "20060102"
+        layout2 = "2006-01-02"
+    )
+    fmt.Println("The next 15 palindromic dates in yyyymmdd format after 20200202 are:")
+    date := time.Date(2020, 2, 2, 0, 0, 0, 0, time.UTC)
+    count := 0
+    for count < 15 {
+        date = date.AddDate(0, 0, 1)
+        s := date.Format(layout)
+        r := reverse(s)
+        if r == s {
+            fmt.Println(date.Format(layout2))
+            count++
+        }
+    }
+}

Task/Palindrome-dates/Go/palindrome-dates-2.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+    "fmt"
+    "sort"
+    "time"
+)
+
+func reverse(s string) string {
+    chars := []rune(s)
+    for i, j := 0, len(chars)-1; i < j; i, j = i+1, j-1 {
+        chars[i], chars[j] = chars[j], chars[i]
+    }
+    return string(chars)
+}
+
+func findIndex(sl []string, s string) int {
+    return sort.Search(len(sl), func(i int) bool {
+        return sl[i] > s
+    })
+}
+
+func main() {
+    const (
+        layout  = "20060102"
+        layout2 = "2006-01-02"
+    )
+    palins := []string{}
+    for i := 0; i < 10000; i++ {
+        y := fmt.Sprintf("%04d", i)
+        r := reverse(y)
+        if r[:2] > "12" || r[2:] > "31" {
+            continue
+        }
+        d := fmt.Sprintf("%s%s", y, r)
+        t, err := time.Parse(layout, d)
+        if err == nil {
+            palins = append(palins, t.Format(layout2))
+        }
+    }
+    le := len(palins)
+    i1 := findIndex(palins, "1001-01-01")
+    i2 := findIndex(palins, "2020-02-02")
+    fmt.Printf("There are %d palindromic dates after 0000-01-01 of which:\n", le)
+    fmt.Printf("          %d are after 1000-01-01\n", le-i1)
+    fmt.Printf("          %d are after 2020-02-02\n", le-i2)
+    fmt.Println("\nThe first 15 after 2020-02-02 are:")
+    for i := 0; i < 15; i++ {
+        if i != 0 && i%5 == 0 {
+            fmt.Println()
+        }
+        fmt.Printf("%s   ", palins[i+i2])
+    }
+    fmt.Println("\n\nThe last 15 before 9999-12-31 are:")
+    for i := 15; i >= 1; i-- {
+        if i != 15 && i%5 == 0 {
+            fmt.Println()
+        }
+        fmt.Printf("%s   ", palins[le-i])
+    }
+    fmt.Println()
+}