广度+深度优先搜索

from collections import deque
direction = [[0,1],[1,0],[0,-1],[-1,0]]
'''
def bfs(graph,visited,a,b):
    que = deque([])
    que.append([a,b])
    visited[a][b] = True
    while que:
        i,j = que.popleft()
        for x,y in direction:
            cur_x = i+x
            cur_y = j+y
            if cur_x<0 or cur_y<0 or cur_x>=len(graph) or cur_y>= len(graph[0]):
                continue
            if visited[cur_x][cur_y] == False and graph[cur_x][cur_y] == 1:
                visited[cur_x][cur_y] = True
                que.append([cur_x,cur_y]) # 输入当前的坐标，方便好吗搜索


def main():
    n,m = map(int,input().split())
    graph = []
    res = 0
    for i in range(n):
        num = list(map(int,input().split()))
        graph.append(num)
    visited = [[False]*m for _ in range(n)]
    for i in range(n):
        for j in range(m):
            if graph[i][j] == 1 and visited[i][j] == False:
                res += 1
                bfs(graph,visited,i,j)
    print(res)
'''
def dfs(graph,visited,x,y):
    if graph[x][y] == 0 or visited[x][y] :
        return 
    visited[x][y] = True
    for i,j in direction:
        cur_x = x+i
        cur_y = y+j
        if cur_x<0 or cur_y<0 or cur_x >=len(graph) or cur_y>=len(graph[0]):
            continue
        dfs(graph,visited,cur_x,cur_y)




def main():
    n,m = map(int,input().split())
    graph = []
    for i in range(n):
        num = list(map(int,input().split()))
        graph.append(num)
    visited = [[False]*m for _ in range(n)]
    res = 0
    for i in range(n):
        for j in range(m):
            if graph[i][j] == 1 and visited[i][j] == False:
                res += 1
                dfs(graph,visited,i,j)
    print(res)


if __name__ == '__main__':
    main()

99. 岛屿数量