代码随想录算法训练营DAY57｜岛屿数量、岛屿的最大面积

岛屿数量 深搜

def dfs(x, y, graph):
    if x<0 or x>=len(graph) or y<0 or y>=len(graph[0]) or graph[x][y]==0:
        return
    graph[x][y]=0
    dfs(x+1, y, graph)
    dfs(x-1, y, graph)
    dfs(x, y+1, graph)
    dfs(x, y-1, graph)
    


if __name__=='__main__':
    r,l =map(int,input().split(' '))
    graph = []
    for i in range(r):
        row = list(map(int,input().split(' ')))
        graph.append(row)
    
    result = 0
    for i in range(r):
        for j in range(l):
            if graph[i][j]==1:
                dfs(i,j,graph)
                result+=1
    print(result)

岛屿数量 广搜

from collections import deque

def bfs(x, y, graph):
    graph[x][y]=0
    que = deque([[x,y]])
    while que:
        x, y = que.popleft()
        directions = [[0,1],[0,-1],[1,0],[-1,0]]
        for k in range(4):
            x0, y0 = directions[k]
            new_x = x+x0
            new_y = y+y0
            if new_x>=0 and new_x<len(graph) and new_y>=0 and new_y<len(graph[0]) and graph[new_x][new_y]==1:
                que.append([new_x, new_y])
                graph[new_x][new_y]=0
    return     
        
        
    


if __name__=='__main__':
    r,l =map(int,input().split(' '))
    graph = []
    for i in range(r):
        row = list(map(int,input().split(' ')))
        graph.append(row)
    
    result = 0
    for i in range(r):
        for j in range(l):
            if graph[i][j]==1:
                bfs(i,j,graph)
                result+=1
    print(result)

岛屿的最大面积

• bfs

from collections import deque

def bfs(x, y, graph):
    s=1
    graph[x][y]=0
    que = deque([[x,y]])
    while que:
        x, y = que.popleft()
        directions = [[0,1],[0,-1],[1,0],[-1,0]]
        for k in range(4):
            x0, y0 = directions[k]
            new_x = x+x0
            new_y = y+y0
            if new_x>=0 and new_x<len(graph) and new_y>=0 and new_y<len(graph[0]) and graph[new_x][new_y]==1:
                que.append([new_x, new_y])
                graph[new_x][new_y]=0
                s+=1
    return s
        
        
    


if __name__=='__main__':
    r,l =map(int,input().split(' '))
    graph = []
    for i in range(r):
        row = list(map(int,input().split()))
        graph.append(row)
    
    result = 0
    for i in range(r):
        for j in range(l):
            if graph[i][j]==1:
                s = bfs(i,j,graph)
                result = max(result, s)
    print(result)

• dfs

def dfs(x, y, graph, s):
    if x<0 or x>=len(graph) or y<0 or y>=len(graph[0]) or graph[x][y]==0:
        return s
    graph[x][y]=0
    s+=1
    s = dfs(x+1, y, graph, s)
    s = dfs(x-1, y, graph, s)
    s = dfs(x, y+1, graph, s)
    s = dfs(x, y-1, graph, s)
    return s
    
if __name__=='__main__':
    r,l =map(int,input().split())
    graph = []
    for i in range(r):
        row = list(map(int,input().split()))
        graph.append(row)
    
    result = 0
    for i in range(r):
        for j in range(l):
            if graph[i][j]==1:
                s = dfs(i,j,graph,0)
                result = max(result, s)
    print(result)