Island Perimeter – Leetcode Challenge – Java Solution

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This is the java solution for the Leetcode problem – Island Perimeter – Leetcode Challenge – Java Solution.

Source – qiyuangong’s repository.

class Solution {
    public int islandPerimeter(int[][] grid) {
        // https://leetcode.com/problems/island-perimeter/discuss/95001/clear-and-easy-java-solution
        int islands = 0, neighbours = 0;
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[i].length; j++) {
                if (grid[i][j] == 1) {
                    islands++; // count islands
                    if (i < grid.length - 1 && grid[i + 1][j] == 1) neighbours++; // count down neighbours
                    if (j < grid[i].length - 1 && grid[i][j + 1] == 1) neighbours++; // count right neighbours
                }
            }
        }
        return islands * 4 - neighbours * 2;
    }
}