Puzzle 1, part B

1b.go

package main

import (
  "bufio"
  "os"
  "fmt"
)

func main() {
  var i, j, sum int
  ns, m, s := []int{}, map[int]int{}, bufio.NewScanner(os.Stdin)
  for s.Scan() {
    if n, _ := fmt.Sscanf(s.Text(), "%d %d", &i, &j); 2 == n {
      ns = append(ns, i)
      m[j]++
    }
  }
  for _, n := range(ns) {
    sum += n * m[n]
  }
  fmt.Printf("%d\n", sum)
}