2016-1A Problem B

Final solution

// package, import, etc...

func start() {
  // read T, repeat test() T times...
}

func test() {
	var N int
	mustReadLineOfInts(&N)
	heightsSeen := make(map[int]int)
	for i := 0; i < 2*N-1; i++ {
		list := mustReadLineOfIntsIntoArray()
		assert(len(list) == N)
		for _, height := range list {
			heightsSeen[height]++
		}
	}
	oddHeights := make([]int, 0, N)
	for height, count := range heightsSeen {
		if count%2 == 1 {
			oddHeights = append(oddHeights, height)
		}
	}
	sort.Ints(oddHeights)
	strs := make([]string, 0, N)
	for _, oh := range oddHeights {
		strs = append(strs, strconv.Itoa(oh))
	}
	stdout.WriteString(strings.Join(strs, " "))
	stdout.WriteByte('\n')
}

// boilerplate omitted...

Sample test cases given in question

1
3
1 2 3
2 3 5
3 5 6
2 3 4
1 2 3