go.go

package main

import (
  "fmt"
  "os"
  "io"
)

type Tuple struct {
    is_there bool;
    count int
}

func readFile(file *os.File) (numbers map[int]Tuple) {

    var line int
    numbers = make(map[int]Tuple)

    for {

        _, err := fmt.Fscanf(file, "%d", &line)

        if err == io.EOF {
            return
        }

        if numbers[line].is_there {
            numbers[line] = Tuple{true, numbers[line].count + 1}
        } else {
            numbers[line] = Tuple{true, 1}
        }
    }
}

func main() {

  filename := "input.txt"
  file, _ := os.Open(filename)

  var target int

  fmt.Fscanf(file, "%d\n",  &target)

  numbers := readFile(file)

  output, _ := os.Create("output.txt")

  for key, _ := range numbers {

      needed_value := target - key
      if numbers[needed_value].is_there {

          if needed_value == key && numbers[needed_value].count == 1 {
              continue
          }

          output.WriteString("1\n")
          return
      }
  }

  output.WriteString("0\n")
}