[habitica] Programming challenge July 2019

package main

import (
    "strconv"
    "strings"
    "os"
    "fmt"
    "bufio"
)

func main() {
    reader := bufio.NewReader(os.Stdin)
    fmt.Print("Input your problem: ")
    input, _ := reader.ReadString('\n')
    problem := strings.TrimSuffix(strings.TrimSuffix(string(input), "?\n"), "\n")
    problemSlice := strings.Split(problem, " ")

    var result *int

    for i, el := range problemSlice {
        switch el {
        case "plus":
            if result == nil {
                a, _ := strconv.Atoi(problemSlice[i-1])
                result = &a
            }
            b, _ := strconv.Atoi(problemSlice[i+1])
            x := *result + b
            result = &x
        case "minus":
            if result == nil {
                a, _ := strconv.Atoi(problemSlice[i-1])
                result = &a
            }
            b, _ := strconv.Atoi(problemSlice[i+1])
            x := *result - b
            result = &x
        case "multiplied":
            if result == nil {
                a, _ := strconv.Atoi(problemSlice[i-1])
                result = &a
            }
            b, _ := strconv.Atoi(problemSlice[i+2])
            x := *result * b
            result = &x
        case "divided":
            if result == nil {
                a, _ := strconv.Atoi(problemSlice[i-1])
                result = &a
            }
            b, _ := strconv.Atoi(problemSlice[i+2])
            x := *result / b
            result = &x
        }
    }
    fmt.Println(*result)
}