題目
給定一個由?'1'(陸地)和?'0'(水)組成的的二維網格,計算島嶼的數量。一個島被水包圍,并且它是通過水平方向或垂直方向上相鄰的陸地連接而成的。你可以假設網格的四個邊均被水包圍。
示例 1:輸入:
11110
11010
11000
00000輸出: 1
示例?2:輸入:
11000
11000
00100
00011輸出: 3
思路
DFS,深度遍歷搜索
visited記錄遍歷過的陸地
代碼
class Solution:def numIslands(self, grid: List[List[str]]) -> int:if len(grid) == 0:return 0#visited全部初始化為0row, col = len(grid), len(grid[0])visited = [[0 for x in range(0, col)] for y in range(0, row)]count=0for i in range(0,row):for j in range(0,col):if visited[i][j]==0 and grid[i][j]=='1':self.dfs(grid,i,j,visited)count += 1return countdef dfs(self, grid, i, j, visited):if i < 0 or i >= len(grid):returnif j < 0 or j >= len(grid[0]):returnif grid[i][j]=='0' or visited[i][j]==1:returnvisited[i][j] = 1 #遍歷過的地方置為1#上下左右四個方向遍歷self.dfs(grid, i-1, j, visited)self.dfs(grid, i+1, j, visited)self.dfs(grid, i, j-1, visited)self.dfs(grid, i, j+1, visited)