package main

import (
	"fmt"
	"os"
)

func numEquivDominoPairs(dominoes [][]int) int {
	var ret int = 0

	var out_size int = len(dominoes)

	var seen map[string][]int = make(map[string][]int)
	var ok bool

	var i int = 0
	for i = 0; i < out_size; i += 1 {
		var a, b rune = rune(dominoes[i][0]), rune(dominoes[i][1])

		var key string = string([]rune{a, b})

		var idxs []int
		idxs, ok = seen[key]
		if ok { seen[key] = append(idxs, i); continue }

		var inv_key string = string([]rune{b, a})
		idxs, ok = seen[inv_key]
		if ok { seen[inv_key] = append(idxs, i); continue }

		seen[key] = []int{ i }
	}

	permuts_num := func (list []int) int {
		var ret int = 0

		var list_size int = len(list)
		var i int = 0
		for ; i < list_size; i += 1 {
			var j int = i+1
			for ; j < list_size; j += 1 { ret += 1 }
		}

		return ret
	}

	for _, v := range seen { ret += permuts_num(v) }

	return ret
}

func main() {
	r := func(dominoes [][]int, exp int) {
		fmt.Printf(
			"numEquivDominoPairs(%v) = %v | exp: %v\n", dominoes,
			numEquivDominoPairs(dominoes), exp,
		)
	}

	r([][]int{{1, 2}, {2, 1}, {3, 4}, {5, 6}}, 1)
	r([][]int{{1, 2}, {1, 2}, {1, 1}, {1, 2}, {2, 2}}, 3)
	r([][]int{{2, 1}, {1, 2}, {1, 2}, {1, 2}, {2, 1}, {1, 1}, {1, 2}, {2, 2}}, 15)

	os.Exit(0)
}