contestF.go

package main

import (
	"bufio"
	"io/ioutil"
	"os"
	"strconv"
)

const (
	inputFile    string = "input.txt"
	outputFile   string = "output.txt"
	defaultPerms        = 0644
)

func main() {
	vars := make(map[int]int, 0)
	file, _ := os.Open(inputFile)
	defer file.Close()

	reader := bufio.NewReader(file)
	targetStr, _ := reader.ReadString('\n')
	target, _ := strconv.Atoi(targetStr[0 : len(targetStr)-1])
	for {
		numStr, err := reader.ReadString(' ')
		if err != nil {
			break
		}
		num, err := strconv.Atoi(numStr[0 : len(numStr)-1])
		if err != nil {
			break
		}
		if _, ok := vars[num]; !ok {
			vars[target-num] = num
		} else {
			ioutil.WriteFile(outputFile, []byte("1"), defaultPerms)
			return
		}
	}
	ioutil.WriteFile(outputFile, []byte("0"), defaultPerms)
}