<p>You are given <code>row x col</code> <code>grid</code> representing a map where <code>grid[i][j] = 1</code> represents&nbsp;land and <code>grid[i][j] = 0</code> represents water.</p>

<p>Grid cells are connected <strong>horizontally/vertically</strong> (not diagonally). The <code>grid</code> is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells).</p>

<p>The island doesn&#39;t have &quot;lakes&quot;, meaning the water inside isn&#39;t connected to the water around the island. One cell is a square with side length 1. The grid is rectangular, width and height don&#39;t exceed 100. Determine the perimeter of the island.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img src="https://assets.leetcode.com/uploads/2018/10/12/island.png" style="width: 221px; height: 213px;" />
<pre>
<strong>Input:</strong> grid = [[0,1,0,0],[1,1,1,0],[0,1,0,0],[1,1,0,0]]
<strong>Output:</strong> 16
<strong>Explanation:</strong> The perimeter is the 16 yellow stripes in the image above.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1]]
<strong>Output:</strong> 4
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1,0]]
<strong>Output:</strong> 4
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>row == grid.length</code></li>
	<li><code>col == grid[i].length</code></li>
	<li><code>1 &lt;= row, col &lt;= 100</code></li>
	<li><code>grid[i][j]</code> is <code>0</code> or <code>1</code>.</li>
	<li>There is exactly one island in <code>grid</code>.</li>
</ul>

class Solution {
private:
    int m;
    int n;
    vector< vector<int>> directions = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
public:
    int find_boundary(vector<vector<int>>& grid, int i, int j){
        int cells = 0;
        // if(i>0 && grid[i-1][j] == 1){
        //     cells++;
        // }

        // if(j>0 && grid[i][j-1] == 1){
        //     cells++;
        // }

        // if(i<m-1 && grid[i+1][j] == 1){
        //     cells++;
        // }

        // if(j<n-1 && grid[i][j+1] == 1){
        //     cells++;
        // }

        for(auto &dir : directions){
            int i_n = i+ dir[0];
            int j_n = j+ dir[1];
            if(i_n <0 || i_n>=m || j_n < 0|| j_n>=n){
                continue;
            }
            else if(grid[i_n][j_n]){
                cells++;
            }
        }

        return 4-cells;
    }

    int islandPerimeter(vector<vector<int>>& grid) {
        int perimeter = 0;
        m = grid.size();
        n = grid[0].size();

        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                if(grid[i][j] == 1){
                    perimeter += find_boundary(grid, i, j);
                }
            }
        }
        return perimeter;
    }
};
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