README.md

A solution to the common interview question of finding odd numbers between two ints

Implemented as a simple REST API

Example

• $ go run main.go
• $ curl http://localhost:8080/api/oddnumbers/1/10 Returns an array of odd numbers in the range

odd numbers in a range

package main

//create an http server with router
import (
	"context"
	"encoding/json"
	"github.com/gorilla/mux"
	"log"
	"net/http"
	"strconv"
	"time"
)

func main() {
	httpServer := &http.Server{
		Addr:         ":8080",
		Handler:      initRouter(),
		ReadTimeout:  5 * time.Second,
		WriteTimeout: 5 * time.Second,
	}
	log.Println("HTTP server is listening ...")
	log.Fatal(httpServer.ListenAndServe())
}

func initRouter() *mux.Router {
	router := mux.NewRouter()
	router.HandleFunc("/api/oddnumbers/{l}/{r}", oddNumbers).Methods("GET")
	return router
}

func oddNumbers(w http.ResponseWriter, req *http.Request) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	vars := mux.Vars(req)
	l, err := strconv.Atoi(vars["l"])
	r, err := strconv.Atoi(vars["r"])
	errorHandler(err, ctx)
	results := findOddNumbersInRange(l, r)

	j, err := json.Marshal(&results)
	errorHandler(err, ctx)

	w.Header().Set("Content-Type", "application/json; charset=utf8")
	w.Write(j)

}

func findOddNumbersInRange(l, r int) []int {
	var results []int

	for i := l; i <= r; i++ {
		if i%2 != 0 {
			results = append(results, i)
		}
	}
	return results
}

func errorHandler(err error, ctx context.Context) {
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	if err != nil {
		log.Fatalf("Error marshaling data %v\n", err.Error())
		cancel()
	}

}