Problem A. Store Credit

gistfile1.go

package main

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

type MyReader struct {
    *bufio.Reader
}

func ReadInt(s string) int {
    num, _ := strconv.ParseInt(strings.TrimRight(s, "\n"), 0, 64)
    return int(num)
}

func (r *MyReader) ReadNextNumber() int {
    line, _ := r.ReadString('\n')
    return ReadInt(line)
}

func (r *MyReader) ReadNextNumbers() (int, map[int]int) {
    money := r.ReadNextNumber()
    length := r.ReadNextNumber()

    line, _ := r.ReadString('\n')
    line = strings.TrimRight(line, "\n")
    lines := strings.Split(line, " ")

    res := make(map[int]int, length)
    for i := 0; i < length; i++ {
        num, _ := strconv.ParseInt(lines[i], 0, 64)
        res[int(num)] = i+1
    }
    return money, res
}

func main() {
    path := flag.String("path", "path", "the path")
    flag.Parse()

    fi, _ := os.Open(*path)
    myReader := &MyReader{bufio.NewReader(fi)}
    defer fi.Close()

    nCases := myReader.ReadNextNumber()
    wg := sync.WaitGroup{}
    result := make([][2]int, nCases)
    for i:=0; i < nCases; i++ {
        wg.Add(1)
        money, items := myReader.ReadNextNumbers()
        go func(i int, money int, items map[int]int) {
            defer wg.Done()
            for num, index := range items {
                remain := money - num
                if items[remain] > 0 {
                    result[i][0] = index -1
                    result[i][1] = items[remain] -1
                    break
                }
            }
        }(i, money, items)
    }
    wg.Wait()
    fmt.Println(result)
}