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:
    B 合约数
    Weekly Contest 80
    第十六届上海大学程序设计联赛春季赛暨上海高校金马五校赛
    2018年长沙理工大学第十三届程序设计竞赛
    通过 DDNS 解决宽带拨号 ip 变化问题
    frp 内网穿透的使用 和原理
    笔记本centos 取消 关闭盖子自动挂起
    centos7 pptp 安装
    linux 命令收集
    centos7 关闭防护墙
  • 原文地址:https://www.cnblogs.com/amazingzoe/p/9034314.html
Copyright © 2011-2022 走看看