pwc245 solution in go

2 files changed, 210 insertions, 0 deletions

diff --git a/challenge-245/pokgopun/go/ch-1.go b/challenge-245/pokgopun/go/ch-1.go
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+++ b/challenge-245/pokgopun/go/ch-1.go
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+//# https://theweeklychallenge.org/blog/perl-weekly-challenge-245/
+/*#
+
+Task 1: Sort Language
+
+Submitted by: [45]Mohammad S Anwar
+     __________________________________________________________________
+
+   You are given two array of languages and its popularity.
+
+   Write a script to sort the language based on popularity.
+
+Example 1
+
+Input: @lang = ('perl', 'c', 'python')
+       @popularity = (2, 1, 3)
+Output: ('c', 'perl', 'python')
+
+Example 2
+
+Input: @lang = ('c++', 'haskell', 'java')
+       @popularity = (1, 3, 2)
+Output: ('c++', 'java', 'haskell')
+
+Task 2: Largest of Three
+#*/
+//# solution by pokgopun@gmail.com
+
+package main
+
+import (
+	"cmp"
+	"fmt"
+	"reflect"
+	"slices"
+)
+
+type ranks []int
+
+type words []string
+
+func (w words) sort(r ranks) words {
+	slices.SortFunc(w, func(a, b string) int {
+		return cmp.Compare(r[slices.Index(w, a)], r[slices.Index(w, b)])
+	})
+	return w
+}
+
+func main() {
+	for _, data := range []struct {
+		input1 words
+		input2 ranks
+		output words
+	}{
+		{words{"perl", "c", "python"}, ranks{2, 1, 3}, words{"c", "perl", "python"}},
+		{words{"c++", "haskell", "java"}, ranks{1, 3, 2}, words{"c++", "java", "haskell"}},
+	} {
+		fmt.Println(reflect.DeepEqual(data.input1.sort(data.input2), data.output))
+	}
+}
diff --git a/challenge-245/pokgopun/go/ch-2.go b/challenge-245/pokgopun/go/ch-2.go
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index 0000000000..74527e790b
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+++ b/challenge-245/pokgopun/go/ch-2.go
@@ -0,0 +1,150 @@
+//# https://theweeklychallenge.org/blog/perl-weekly-challenge-245/
+/*#
+
+Task 2: Largest of Three
+
+Submitted by: [46]Mohammad S Anwar
+     __________________________________________________________________
+
+   You are given an array of integers >= 0.
+
+   Write a script to return the largest number formed by concatenating
+   some of the given integers in any order which is also multiple of 3.
+   Return -1 if none found.
+
+Example 1
+
+Input: @digits = (8, 1, 9)
+Output: 981
+
+981 % 3 == 0
+
+Example 2
+
+Input: @digits = (8, 6, 7, 1, 0)
+Output: 8760
+
+Example 3
+
+Input: @digits = (1)
+Output: -1
+     __________________________________________________________________
+
+   Last date to submit the solution 23:59 (UK Time) Sunday 3rd December
+   2023.
+     __________________________________________________________________
+
+SO WHAT DO YOU THINK ?
+#*/
+//# solution by pokgopun@gmail.com
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"slices"
+)
+
+func main() {
+	for _, data := range []struct {
+		input  digits
+		output int
+	}{
+		{digits{8, 1, 9}, 981},
+		{digits{8, 6, 7, 1, 0}, 8760},
+		{digits{1}, -1},
+	} {
+		fmt.Println(reflect.DeepEqual(data.output, data.input.lot()))
+	}
+}
+
+type digits []int
+
+func (d digits) concat() int {
+	r := d[0]
+	var n, t int
+	for _, v := range d[1:] {
+		n, t = v, 10
+		for n > 10 {
+			t *= 10
+			n /= 10
+		}
+		r = r*t + v
+	}
+	return r
+}
+
+func (d digits) lot() int {
+	slices.Sort(d)
+	slices.Reverse(d)
+	l := len(d)
+	for i := l; i > 0; i-- {
+		res, closer := d.permute(i)
+		for v := range res {
+			r := v.concat()
+			if r%3 == 0 {
+				closer()
+				return r
+			}
+		}
+	}
+	return -1
+}
+
+// transcribed from https://docs.python.org/3/library/itertools.html#itertools.permutations
+func (d digits) permute(r int) (res chan digits, closer func()) {
+	res = make(chan digits)
+	done := make(chan struct{})
+	n := len(d)
+	idx := make([]int, n)
+	for i := range idx {
+		idx[i] = i
+	}
+	cyc := make([]int, r)
+	for i := range cyc {
+		cyc[i] = n - i
+	}
+	go func() {
+		r0 := make(digits, r)
+		copy(r0, d[:r])
+		select {
+		case <-done:
+			close(res)
+			return
+		case res <- r0:
+		}
+		for {
+			for i := r - 1; i >= 0; i-- {
+				cyc[i]--
+				if cyc[i] == 0 {
+					idx = append(idx, idx[i])
+					idx = slices.Delete(idx, i, i+1)
+					cyc[i] = n - i
+				} else {
+					j := cyc[i]
+					idx[i], idx[n-j] = idx[n-j], idx[i]
+					rn := make(digits, r)
+					for i, v := range idx[:r] {
+						rn[i] = d[v]
+					}
+					select {
+					case <-done:
+						close(res)
+						return
+					case res <- rn:
+					}
+					break
+				}
+				if i == 0 {
+					close(res)
+					return
+				}
+			}
+		}
+		close(res)
+	}()
+	return res, func() {
+		close(done)
+	}
+}