написал хендлер для всех задач и для вызова по одной

main.go

@@ -1,10 +1,13 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"gotest/solutions"
-	"io"
+	"log"
 	"net/http"
+	"strings"
+	"sync"
 )
 
 func main() {
@@ -18,5 +21,59 @@ func main() {
 }
 
 func Handler(w http.ResponseWriter, r *http.Request) {
-	io.WriteString(w, "я стану хокаге!!!")
+
+	if r.URL.Path == "/tasks/" {
+		var answers = make([][]byte, 4)
+		var err error
+		var wg sync.WaitGroup //ждёмс рутины
+		wg.Add(4)
+
+		go func() {
+			defer wg.Done()
+			answers[0], err = solutions.ProcessTask(solutions.Rotation)
+			if err != nil {
+				log.Fatalln(err)
+			}
+		}()
+
+		go func() {
+			defer wg.Done()
+			answers[1], err = solutions.ProcessTask(solutions.FindUnique)
+			if err != nil {
+				log.Fatalln(err)
+			}
+		}()
+
+		go func() {
+			defer wg.Done()
+			answers[2], err = solutions.ProcessTask(solutions.Cons)
+			if err != nil {
+				log.Fatalln(err)
+			}
+		}()
+
+		go func() {
+			defer wg.Done()
+			answers[3], err = solutions.ProcessTask(solutions.Missing)
+			if err != nil {
+				log.Fatalln(err)
+			}
+		}()
+
+		wg.Wait()
+		w.Write(bytes.Join(answers, []byte{}))
+
+	} else {
+
+		taskName := strings.Split(r.URL.Path, "/")
+		//fmt.Println(taskName[2])
+		answer, err := solutions.ProcessTask(taskName[2])
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		w.Write(answer)
+
+	}
+
 }

solutions/service.go

@@ -20,7 +20,7 @@ type taskElement struct {
 	result []int
 }
 
-func processTask(taskName string) ([]byte, error) {
+func ProcessTask(taskName string) ([]byte, error) {
 	//получаем условия для задач
 	var taskCases []json.RawMessage
 	err := getCases(taskName, &taskCases)