【DFS】1020.飞地的数量

题目
跟题目1254.统计封闭岛屿的数目完全相同的套路！

DFS

Python

class Solution:
    def numEnclaves(self, grid: List[List[int]]) -> int:
        m, n = len(grid), len(grid[0])
        for i in range(m):
            for j in range(n):
                if (i == 0 or i == m-1 or j == 0 or j == n-1) and grid[i][j] == 1:
                    self.dfs(grid, i, j)
        zero_count = 0
        for i in range(m):
            for j in range(n):
                if grid[i][j] == 0:
                    zero_count += 1
        
        return m*n - zero_count
    
    def dfs(self, grid, i, j):
        if (i < 0 or i >= len(grid) 
            or j < 0 or j >= len(grid[0])
            or grid[i][j] == 0):
            return
        grid[i][j] = 0
        self.dfs(grid, i-1, j)
        self.dfs(grid, i+1, j)
        self.dfs(grid, i, j-1)
        self.dfs(grid, i, j+1)