标签：OLE and color group img must src info site
Given a non-empty 2D array grid of 0‘s and 1‘s, an island is a group of 1‘s (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.
Find the maximum area of an island in the given 2D array. (If there is no island, the maximum area is 0.)
Example 1:
[[0,0,1,0,0,0,0,1,0,0,0,0,0], [0,0,0,0,0,0,0,1,1,1,0,0,0], [0,1,1,0,1,0,0,0,0,0,0,0,0], [0,1,0,0,1,1,0,0,1,0,1,0,0], [0,1,0,0,1,1,0,0,1,1,1,0,0], [0,0,0,0,0,0,0,0,0,0,1,0,0], [0,0,0,0,0,0,0,1,1,1,0,0,0], [0,0,0,0,0,0,0,1,1,0,0,0,0]]Given the above grid, return
6. Note the answer is not 11, because the island must be connected 4-directionally.
Example 2:
[[0,0,0,0,0,0,0,0]]Given the above grid, return
0.
Note: The length of each dimension in the given grid does not exceed 50.
1 public class maxareaofisland { 2 int maxarea = 0; 3 public int maxAreaOfIsland(int[][] grid) { 4 boolean[][] visited = new boolean[grid.length][grid[0].length]; 5 for ( int i = 0 ; i < grid.length ; i ++ ){ 6 for ( int j = 0 ; j < grid[i].length ; j ++ ){ 7 int temparea = helper(i,j,grid,visited); 8 maxarea = Math.max(maxarea,temparea); 9 } 10 } 11 return maxarea; 12 } 13 14 private int helper(int i, int j, int[][] grid, boolean[][] visited) { 15 if ( i < 0 || j < 0 || i > grid.length - 1 || j > grid.length - 1) return 0; 16 if ( grid[i][j] == 0 || visited[i][j]) return 0; 17 visited[i][j] = true; 18 return 1 + helper(i+1,j,grid,visited)+helper(i-1,j,grid,visited)+helper(i,j+1,grid,visited)+helper(i,j-1,grid,visited); 19 } 20 }
运行时间23ms，击败36.30%的提交。
看了一下其他的方法，基本都是深搜。只是一些技巧问题，就不管了。
标签：OLE and color group img must src info site
原文地址：https://www.cnblogs.com/boris1221/p/9367404.html
