<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 {
public:
    bool visited[105][105];
    vector<int> d[4] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
    bool isValid(int i, int j, int row, int col) {
        if (i < 0 || i >= row || j < 0 || j >= col) {
            return false;
        } else {
            return true;
        }
    }
    int islandPerimeter(vector<vector<int>>& grid) {
        int row = grid.size();
        int col = grid[0].size();
        int si=-1;
        int sj=-1;
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col; j++) {
            
                if (grid[i][j] == 1) {
                    si = i;
                    sj = j;
                    break;
                }
                if(si !=-1) 
                {
                    break;
                }
            }
        }
        memset(visited, false, sizeof(visited));
        int count = 0;
        queue<pair<int, int>> q;
        q.push({si, sj});
        visited[si][sj] = true;
        while (!q.empty()) {
            pair<int, int> par = q.front();
            q.pop();
            int si = par.first;
            int sj = par.second;
            for (int i = 0; i < 4; i++) {
                int ci = si + d[i][0];
                int cj = sj + d[i][1];
                if (isValid(ci, cj, row, col) && !visited[ci][cj] && grid[ci][cj]) {
                    q.push({ci, cj});
                    visited[ci][cj] = true;
                }
                if (!isValid(ci, cj, row, col)) {
                    count++;
                }
                else if (grid[ci][cj] == 0) {
                    count++;
                }
            }
        }
        return count;
    }
};
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