go: add «1122. Relative Sort Array»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/relative-sort-array.go

@@ -0,0 +1,31 @@
+package relative_sort_array
+
+import (
+	"cmp"
+	"slices"
+)
+
+func relativeSortArray(arr1 []int, arr2 []int) []int {
+	// remap the keys
+	keys := make(map[int]int, len(arr2))
+	for i, x := range arr2 {
+		keys[x] = i
+	}
+
+	// sort with the given keys
+	slices.SortFunc(arr1, func(x, y int) int {
+		xi, xFound := keys[x]
+		yi, yFound := keys[y]
+
+		if !xFound {
+			xi = 1000 + x
+		}
+		if !yFound {
+			yi = 1000 + y
+		}
+
+		return cmp.Compare(xi, yi)
+	})
+
+	return arr1
+}