Problem B: How Many Islands?

You are given a marine area map represented as a mesh of squares, each denoting land or sea. You can move from one land square to another if they are horizontally, vertically, or diagonally adjacent. Two areas are part of the same island if you can walk from one to the other through other land areas. The marine area is surrounded by sea, so you cannot walk outside the area. Write a program to count the number of islands on the map. The input consists of datasets, each with the format: width, height, followed by the map. 0 represents sea, and 1 represents land. Output the number of islands for each dataset. The input ends with a line containing two zeros.

# Buggy version:
#!/usr/bin/env python
# -*- coding: utf-8 -*-

def dfs(s,Map,H,W,c):
    dxdy = [(1,0),(-1,0),(0,1),(0,-1),(1,1),(-1,-1),(-1,1),(1,-1)]
    for i in range(len(dxdy)):
        Map[s[0]][s[1]] = c
        nextPos = (s[0]+dxdy[i][0],s[1]+dxdy[i][1])
        # if nextPos[0] >= 0 and nextPos[1] >= 0 and nextPos[0] < H and nextPos[1] < W:
        #     if Map[nextPos[0]][nextPos[1]] == 1:
        #         dfs(nextPos,Map,H,W,c)

while True:
    W,H = map(int,input().split(" "))
    if W == 0 and H == 0:
        break
    Map = [list(map(int,input().split())) for i in range(0,H)]
    c = 1
    for i in range(H):
        for j in range(W):
            if Map[i][j] == 1:
                c += 1
                dfs((i,j),Map,H,W,c)
    print(c-1)

# Fixed version:
#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys
sys.setrecursionlimit(10**6)

def dfs(s,Map,H,W,c):
    dxdy = [(1,0),(-1,0),(0,1),(0,-1),(1,1),(-1,-1),(-1,1),(1,-1)]
    for i in range(len(dxdy)):
        Map[s[0]][s[1]] = c
        nextPos = (s[0]+dxdy[i][0],s[1]+dxdy[i][1])
        if nextPos[0] >= 0 and nextPos[1] >= 0 and nextPos[0] < H and nextPos[1] < W:
            if Map[nextPos[0]][nextPos[1]] == 1:
                dfs(nextPos,Map,H,W,c)

while True:
    W,H = map(int,input().split(" "))
    if W == 0 and H == 0:
        break
    Map = [list(map(int,input().split())) for i in range(0,H)]
    c = 1
    for i in range(H):
        for j in range(W):
            if Map[i][j] == 1:
                c += 1
                dfs((i,j),Map,H,W,c)
    print(c-1)

# Buggy version:
import sys
def dfs(tiles, W, H, x, y):
    tiles[y][x] = '0'
    for dx,dy in ((-1,-1), (-1,0), (-1,1), (0,-1), (0,1), (1,-1), (1,0), (1,1)):
        if 0<=x+dx<W and 0<=y+dy<H and tiles[y+dy][x+dx]=='1':
            dfs(tiles, W, H, x+dx, y+dy)
    return

def main():
    while True:
        W,H = [int(x) for x in input().split()]
        if W==0 and H==0:
            exit()
        tiles = [[c for c in input().split()] for h in range(H)]
        cnt = 0
        for h in range(H):
            for w in range(W):
                if tiles[h][w] == '1':
                    cnt += 1
                    dfs(tiles, W, H, w, h)
        print(cnt)

if __name__ == '__main__':
    sys.getrecursionlimit(10000)
    main()

# Fixed version:
import sys
def dfs(tiles, W, H, x, y):
    tiles[y][x] = '0'
    for dx,dy in ((-1,-1), (-1,0), (-1,1), (0,-1), (0,1), (1,-1), (1,0), (1,1)):
        if 0<=x+dx<W and 0<=y+dy<H and tiles[y+dy][x+dx]=='1':
            dfs(tiles, W, H, x+dx, y+dy)
    return

def main():
    while True:
        W,H = [int(x) for x in input().split()]
        if W==0 and H==0:
            exit()
        tiles = [input().split() for h in range(H)]
        cnt = 0
        for h in range(H):
            for w in range(W):
                if tiles[h][w] == '1':
                    cnt += 1
                    dfs(tiles, W, H, w, h)
        print(cnt)

if __name__ == '__main__':
    sys.setrecursionlimit(10000)
    main()

# Buggy version:
import sys
sys.setrecursionlimit(1<<32)
def f(x,y):
    a[y][x]='0'
    for dx,dy in[[-1,0],[1,0],[0,-1],[0,1],[-1,-1],[1,-1],[-1,1],[1,1]]:
        dx+=x;dy+=y
        if 0<=dx<w and 0<=dy<h and a[dy][dx]=='1':f(dx,dy)
while 1:
    w,h=map(int,input().split())
    if w==0:break
    a=[list(input().split()) for _ in[0]*h];b=0
    for i in range(w):
        for j in range(h):
            if a[j][i]=='1':
                b+=1;f(i,j)
    print(b)

# Fixed version:
import sys
sys.setrecursionlimit(10000)
def f(x,y):
    if 0<=x<w and 0<=y<h and a[y][x]=='1':
        a[y][x]='0'
        for dx,dy in[[-1,0],[1,0],[0,-1],[0,1],[-1,-1],[1,-1],[-1,1],[1,1]]:f(x+dx,y+dy)
while 1:
    w,h=map(int,input().split())
    if w==0:break
    a=[input().split() for _ in[0]*h];b=0
    for i in range(w):
        for j in range(h):
            if a[j][i]=='1':
                b+=1;f(i,j)
    print(b)