Go: // AOJ 1160: How Many Islands? http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1160

package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
)

var SEA = 0
var LAND = 1

func nextInt(sc *bufio.Scanner) int {
	sc.Scan()
	v, _ := strconv.Atoi(sc.Text())
	return v
}

func discoverIslands(M, V [][]int, H, W int) int {
	// 島を探す
	queue := list.New()
	islands := 0
	for i := 1; i <= H; i++ {
		for j := 1; j <= W; j++ {
			// 訪問済みの土地ならスキップ
			if V[i][j] == 1 {
				continue
			}

			// 訪問中の土地が海なら訪問済みにしてスキップ
			if M[i][j] == SEA {
				V[i][j] = 1
				continue
			}

			// 未訪問の陸地が見つかったので
			// 島の数を1つ増やし、この陸地から辿れる陸地を訪問していく
			islands++
			queue.PushBack([]int{i, j})

			for queue.Len() > 0 {
				cur := queue.Remove(queue.Front()).([]int)
				h, w := cur[0], cur[1]
				if V[h][w] == 1 {
					continue
				}
				V[h][w] = 1

				// 全方向に未訪問の陸地がないか探索
				for v := -1; v <= 1; v++ {
					for l := -1; l <= 1; l++ {
						dh := h + v
						dw := w + l
						if M[dh][dw] == LAND && V[dh][dw] == 0 {
							queue.PushBack([]int{dh, dw})
						}
					}
				}
				/*
					if M[h-1][w] == LAND {
						queue.PushBack([]int{h - 1, w})
					}
					if M[h-1][w+1] == LAND {
						queue.PushBack([]int{h - 1, w + 1})
					}
					if M[h][w+1] == LAND {
						queue.PushBack([]int{h, w + 1})
					}
					if M[h+1][w+1] == LAND {
						queue.PushBack([]int{h + 1, w + 1})
					}
					if M[h+1][w] == LAND {
						queue.PushBack([]int{h + 1, w})
					}
					if M[h+1][w-1] == LAND {
						queue.PushBack([]int{h + 1, w - 1})
					}
					if M[h][w-1] == LAND {
						queue.PushBack([]int{h, w - 1})
					}
					if M[h-1][w-1] == LAND {
						queue.PushBack([]int{h - 1, w - 1})
					}
				*/
			}
		}
	}
	return islands
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)

	for {
		W, H := nextInt(sc), nextInt(sc)

		if W == 0 && H == 0 {
			break
		}
		// Initialize map and visted list
		M := make([][]int, H+2)
		V := make([][]int, H+2)
		for i := 0; i < H+2; i++ {
			M[i] = make([]int, W+2)
			V[i] = make([]int, W+2)
		}
		for i := 1; i <= H; i++ {
			for j := 1; j <= W; j++ {
				M[i][j] = nextInt(sc)
			}
		}

		islands := discoverIslands(M, V, H, W)

		fmt.Println(islands)
	}
}

Python: import sys
sys.setrecursionlimit(10000)
def bom(i,j):
    for s in range(-1,2):
        for d in range(-1,2):
            if i+s==-1 or i+s==h or j+d==-1 or j+d==w:
                continue
            if l[i+s][j+d]==1:
                l[i+s][j+d]=0
                bom_2(i+s,j+d)
                return 1
    return 0
def bom_2(i,j):
    for s in range(-1,2):
        for d in range(-1,2):
            if i+s==-1 or i+s==h or j+d==-1 or j+d==w:
                continue
            if l[i+s][j+d]==1:
                l[i+s][j+d]=0
                bom_2(i+s,j+d)                
while True:
    w,h=map(int,input().split())
    if w==0:break
    l=[list(map(int,input().split())) for _ in range(h)]
    ans=0
    for i in range(h):
        for j in range(w):
            if l[i][j]==1:
                ans+=bom(i,j)
    print(ans)

Python: import sys
sys.setrecursionlimit(2500)
 
def erase(x, y):
    c[y][x] = '0'
    for dx, dy in ((1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1), (0, -1), (1, -1)):
        nx, ny = x + dx, y + dy
        if 0 <= nx < w and 0 <= ny < h and c[ny][nx] == '1':
            erase(nx, ny)
 
while True:
    w, h = map(int, input().split())
    if w == h == 0:
        break
    c = [input().split() for _ in range(h)]
    ans = 0
    for y in range(h):
        for x in range(w):
            if c[y][x] == '1':
                ans += 1
                erase(x, y)
    print(ans)

Python: import sys
sys.setrecursionlimit(10**8) #再帰関数の上限を変更
ans = []
def dfs(x, y):
    c[x][y] = 0 #今いる場所を0にする
    for dx in range(-1, 2):
        for dy in range(-1, 2):
            nx = x + dx
            ny = y + dy
            ##動く先が範囲内で、1であれば移動する
            if 0 <= nx < h and 0 <= ny < w and c[nx][ny] == 1:
                dfs(nx, ny)
while True:
    w, h = map(int, input().split())
    if w == 0 and h ==0:
        break
    count = 0
    c = [[] for _ in range(h)]
    for i in range(h):
        if w == 1:
            c[i] = [int(input())]
        else:
            c[i] = list(map(int, input().split()))
            #c = [[1, 0, 1, 0, 0], [1, 0, 0, 0, 0], [1, 0, 1, 0, 1], [1, 0, 0, 1, 0]]
    for x in range(h):
        for y in range(w):
            if c[x][y] == 1:
                dfs(x, y)
                count += 1
    ans.append(count)
for i in ans:
    print(i)

Python: while True:
    w, h = map(int, input().split())
    if w == 0 and h == 0:
        break
    cnt = 0
    maps = [list(map(int, input().split())) for _ in range(h)]
    for x in range(w):
        for y in range(h):
            if maps[y][x] == 0:
                continue
            else:
                cnt += 1
                maps[y][x] = 0
                stack = [(y, x)]
                while stack:
                    f_y, f_x = stack.pop()
                    for dy in range(-1, 2):
                        for dx in range(-1, 2):
                            t_y = f_y + dy
                            t_x = f_x + dx
                            if 0 <= t_y <= h - 1 and 0 <= t_x <= w - 1 and maps[t_y][t_x] == 1:
                                maps[t_y][t_x] = 0
                                stack.append((t_y, t_x))
    print(cnt)

Python: class UnionSet:
        def __init__(self, nmax):
            self.size = [1]*nmax
            self.id = [i for i in range(nmax+1)]
        def root(self, i):
            while i != self.id[i]:
                self.id[i] = self.id[self.id[i]]
                i = self.id[i]
            return i
        def connected(self, p, q): return self.root(p) == self.root(q)
        def unite(self, p, q):
            i, j = self.root(p), self.root(q)
            if i == j: return
            if self.size[i] < self.size[j]:
                self.id[i] = j
                self.size[j] += self.size[i]
            else:
                self.id[j] = i
                self.size[i] += self.size[j]
    # UNION-FIND library
     
def id(r, c):
        global w
        return r*w+c

mv = [[-1,-1],[-1,0],[-1,1],[0,-1],[0,1],[1,-1],[1,0],[1,1]]

while True:
        w, h = map(int, input().split())
        if w == 0: break
        arr = [[] for r in range(h)]
        u = UnionSet(w*h)
        for r in range(h): arr[r] = list(map(int, input().split()))
        for r in range(h):
                for c in range(w):
                        if not arr[r][c]: continue
                        for i in range(8):
                                r2, c2 = r + mv[i][0], c + mv[i][1]
                                if r2 < 0 or r2 >= h or c2 < 0 or c2 >= w or not arr[r2][c2]: continue
                                u.unite(id(r, c), id(r2, c2))
        ans = 0
        for r in range(h):
                for c in range(w):
                        if arr[r][c] and u.root(id(r, c)) == id(r, c): ans += 1
        print(ans)