Problem:
Score : 300 points

Problem Statement

There is a grid with H rows and W columns, where each square is painted black or white.

You are given H strings S_1, S_2, ..., S_H, each of length W.
If the square at the i-th row from the top and the j-th column from the left is painted black, the j-th character in the string S_i is #; if that square is painted white, the j-th character in the string S_i is ..

Find the number of pairs of a black square c_1 and a white square c_2 that satisfy the following condition:

There is a path from the square c_1 to the square c_2 where we repeatedly move to a vertically or horizontally adjacent square through an alternating sequence of black and white squares: black, white, black, white...

Constraints

1 \leq H, W \leq 400

|S_i| = W (1 \leq i \leq H)

For each i (1 \leq i \leq H), the string S_i consists of characters # and ..

Input

Input is given from Standard Input in the following format:

H W
S_1
S_2
:
S_H

Output

Print the answer.

Sample Input 1

3 3
.#.
..#
#..

Sample Output 1

10

Some of the pairs satisfying the condition are ((1, 2), (3, 3)) and ((3, 1), (3, 2)), where (i, j) denotes the square at the i-th row from the top and the j-th column from the left.

Sample Input 2

2 4
....
....

Sample Output 2

0

Sample Input 3

4 3
###
###
...
###

Sample Output 3

6

Solution in Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"log"
	"math"
	"os"
	"strconv"
)

var H, W int
var S []string

var dy = []int{1, 0, -1, 0}
var dx = []int{0, 1, 0, -1}

var cnt int
var blackCnt int

// var points []Point
var pass []int
var check []int

func main() {
	log.SetFlags(log.Lshortfile)
	H = nextInt()
	W = nextInt()
	S = make([]string, H)
	if H*W > 80000 {
		fmt.Println("-1")
		return
	}
	for i := 0; i < H; i++ {
		S[i] = nextString()
	}
	ans := 0
	pass = make([]int, H*W)
	for i := 0; i < H; i++ {
		for j := 0; j < W; j++ {
			cnt = 0
			blackCnt = 0
			if S[i][j] == '#' && pass[i*W+j] == 0 {
				blackCnt++
				check = make([]int, H*W)
				check[i*W+j]++
				s(i, j)
				ans += cnt * blackCnt
			}
		}
	}
	fmt.Println(ans)
}
func s(h int, w int) {
	check[h*W+w]++
	for d := 0; d < 4; d++ {
		ny := h + dy[d]
		nx := w + dx[d]
		if ny >= 0 && ny < H && nx >= 0 && nx < W {
			if check[ny*W+nx] > 0 {
				continue
			}
			if S[ny][nx] != S[h][w] {
				if S[ny][nx] == '.' {
					cnt++
				} else {
					pass[ny*W+nx]++
					blackCnt++
				}
				check[ny*W+nx]++
				s(ny, nx)
			}
		}
	}
}

func intPow(a, b int) int {
	return int(math.Pow(float64(a), float64(b)))
}

func lcm(a, b int) int {
	return a * b / gcd(a, b)
}
func gcd(a, b int) int {
	if a < b {
		a, b = b, a
	}
	for b != 0 {
		a, b = b, a%b
	}
	return a
}
func intMax(a ...int) int {
	r := a[0]
	for i := 0; i < len(a); i++ {
		if r < a[i] {
			r = a[i]
		}
	}
	return r
}
func intMin(a ...int) int {
	r := a[0]
	for i := 0; i < len(a); i++ {
		if r > a[i] {
			r = a[i]
		}
	}
	return r
}
func intSum(a []int) (r int) {
	for i := range a {
		r += a[i]
	}
	return r
}
func intAbs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

type pair struct {
	a, b int
}

type pairs []pair

func (p pairs) Len() int {
	return len(p)
}
func (p pairs) Swap(i, j int) {
	p[i], p[j] = p[j], p[i]
}

func (p pairs) Less(i, j int) bool {
	return p[i].b < p[j].b
}

var nextReader func() string

func init() {
	nextReader = newScanner()
}

func newScanner() func() string {
	r := bufio.NewScanner(os.Stdin)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)
	return func() string {
		r.Scan()
		return r.Text()
	}
}
func nextString() string {
	return nextReader()
}
func nextInt64() int64 {
	v, _ := strconv.ParseInt(nextReader(), 10, 64)
	return v
}
func nextInt() int {
	v, _ := strconv.Atoi(nextReader())
	return v
}
func nextInts(n int) []int {
	r := make([]int, n)
	for i := 0; i < n; i++ {
		r[i] = nextInt()
	}
	return r
}
func nextFloat64() float64 {
	f, _ := strconv.ParseFloat(nextReader(), 64)
	return f
}