leetcode Max Area of Island Solution (Max Area of Island) (leetcode june 2021 challenge)

Max Area of Island

You are given an m x n binary matrix grid. 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.

The area of an island is
the number of cells with a value 1 in the island.

Return the maximum area of an
island in grid.
If there is no island, return 0.

Example 1:

Example 1:

Input: grid =
[[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]]

Output: 6

Explanation: The answer is
not 11, because the island must be connected 4-directionally.

Example 2:

Input: grid =
[[0,1,1,1,0,0,0,0]]

Output: 3

Constraints:

·
m == grid.length

·
n == grid[i].length

·
1 <= m, n <= 50

·
grid[i][j] is either 0 or 1.

Solution 1:

public class maxAreaOfIsland {

    public static int length(int[][] grid, int i, int j) {
        if (i >= grid.length || j >= grid[0].length || i < 0 || j < 0 || grid[i][j] != 1)
            return 0;
        int ans = 0;
        grid[i][j] = 2;
        if (j + 1 < grid[0].length && grid[i][j + 1] == 1)
            ans = ans + 1 + length(grid, i, j + 1);
        if (i + 1 < grid.length && grid[i + 1][j] == 1)
            ans = ans + 1 + length(grid, i + 1, j);
        if (j – 1 >= 0 && grid[i][j – 1] == 1)
            ans = ans + 1 + length(grid, i, j – 1);
        if (i – 1 >= 0 && grid[i – 1][j] == 1)
            ans = ans + 1 + length(grid, i – 1, j);
        return ans;
    }
    public static int Solution(int[][] grid) {
        int ans = 0;
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[0].length; j++) {
                if (grid[i][j] == 1)
                    ans = Math.max(ans, length(grid, i, j) + 1);
            }
        }
        return ans;
    }

leetcode Max Area of Island Solution (Max Area of Island) (leetcode june 2021 challenge)

Sandeep Sokle

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