zoukankan      html  css  js  c++  java
  • Max Area of Island

    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.

    Solution

    class Solution {
        public int maxAreaOfIsland(int[][] grid) {
            int maxArea = 0;
            
            for (int i = 0; i < grid.length; i++) {
                for (int j = 0; j < grid[0].length; j++) {
                    if (grid[i][j] == 1) {
                        maxArea = Math.max(maxArea, calculateMaxArea(grid, i, j));
                    }
                }
            }
            
            return maxArea;
        }
        
        private int calculateMaxArea(int[][] grid, int i, int j) {
            if (i >= grid.length || j >= grid[0].length ||
                i < 0 || j < 0 || grid[i][j] != 1) {
                return 0;
            }
            
            grid[i][j] = -1;
            
            return calculateMaxArea(grid, i + 1, j) + 
                   calculateMaxArea(grid, i - 1, j) + 
                   calculateMaxArea(grid, i, j + 1) +
                   calculateMaxArea(grid, i, j - 1) + 1;
        }
    }
  • 相关阅读:
    公用导航栏的根据url控制选中导航js
    页面切换出动晃动解决
    redis五大数据类型
    redis简介
    Linux安装redis
    各种锁的理解
    原子引用
    理解CAS
    彻底玩转单例模式
    Volatile
  • 原文地址:https://www.cnblogs.com/amazingzoe/p/9034314.html
Copyright © 2011-2022 走看看