Utility function to sort with key

tools/utils/misc.go

@@ -5,6 +5,8 @@ package utils
 import (
 	"fmt"
 	"sort"
+
+	"golang.org/x/exp/constraints"
 )
 
 var _ = fmt.Print
@@ -33,3 +35,21 @@ func StableSort[T any](s []T, less func(a, b T) bool) []T {
 	sort.SliceStable(s, func(i, j int) bool { return less(s[i], s[j]) })
 	return s
 }
+
+func SortWithKey[T any, C constraints.Ordered](s []T, key func(a T) C) []T {
+	mem := make([]C, len(s))
+	for i, x := range s {
+		mem[i] = key(x)
+	}
+	sort.Slice(s, func(i, j int) bool { return mem[i] < mem[j] })
+	return s
+}
+
+func StableSortWithKey[T any, C constraints.Ordered](s []T, key func(a T) C) []T {
+	mem := make([]C, len(s))
+	for i, x := range s {
+		mem[i] = key(x)
+	}
+	sort.SliceStable(s, func(i, j int) bool { return mem[i] < mem[j] })
+	return s
+}