LeetCode hot100——200.岛屿数量

题目给你一个由1陆地和0水组成的的二维网格请你计算网格中岛屿的数量。岛屿总是被水包围并且每座岛屿只能由水平方向和/或竖直方向上相邻的陆地连接形成。此外你可以假设该网格的四条边均被水包围。示例 1输入grid [ [1,1,1,1,0], [1,1,0,1,0], [1,1,0,0,0], [0,0,0,0,0] ]输出1示例 2输入grid [ [1,1,0,0,0], [1,1,0,0,0], [0,0,1,0,0], [0,0,0,1,1] ]输出3提示m grid.lengthn grid[i].length1 m, n 300grid[i][j]的值为0或1题解class Solution { public int numIslands(char[][] grid) { int count 0; for(int i 0; igrid.length;i){ for(int j 0;jgrid[0].length;j){ if(grid[i][j] 1){ dfs(grid,i,j); count; } } } return count; } private void dfs(char[][] grid,int r,int c){ if(!isLand(grid,r,c)) return; if(grid[r][c] ! 1) return; //已遍历标记为2 grid[r][c] 2; dfs(grid,r - 1,c); dfs(grid,r 1,c); dfs(grid,r,c - 1); dfs(grid,r,c 1); } //判断是否是陆地 private boolean isLand(char[][] grid,int r,int c){ return r 0 r grid.length c 0 c grid[0].length; } }