<p>You are given an <code>n x n</code> binary matrix <code>grid</code> where <code>1</code> represents land and <code>0</code> represents water.</p>

<p>An <strong>island</strong> is a 4-directionally connected group of <code>1</code>&#39;s not connected to any other <code>1</code>&#39;s. There are <strong>exactly two islands</strong> in <code>grid</code>.</p>

<p>You may change <code>0</code>&#39;s to <code>1</code>&#39;s to connect the two islands to form <strong>one island</strong>.</p>

<p>Return <em>the smallest number of </em><code>0</code><em>&#39;s you must flip to connect the two islands</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

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

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

<pre>
<strong>Input:</strong> grid = [[0,1,0],[0,0,0],[0,0,1]]
<strong>Output:</strong> 2
</pre>

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

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

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

<ul>
	<li><code>n == grid.length == grid[i].length</code></li>
	<li><code>2 &lt;= n &lt;= 100</code></li>
	<li><code>grid[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
	<li>There are exactly two islands in <code>grid</code>.</li>
</ul>

class Solution {
public:
    vector<int> xDirection = {-1, 1, 0, 0};
    vector<int> yDirection = {0, 0, -1, 1};

    void dfs(vector<vector<int>>& grid, int i, int j, vector<vector<int>>& temp)
    {
        if(i<0 || i>=grid.size() || j<0 || j>=grid[0].size())
        {
            return; 
        }

        if(grid[i][j]==0)
        {
            return;
        }

        grid[i][j]=0;
        temp.push_back({i, j});

        for(int a=0;a<4;a++)
        {
            int xTemp = i+xDirection[a];
            int yTemp = j+yDirection[a];

            dfs(grid, xTemp, yTemp,temp);
        }
    }
    int shortestBridge(vector<vector<int>>& grid) {
        vector<vector<vector<int>>> island;

        for(int i=0;i<grid.size();i++)
        {
            for(int j=0;j<grid[0].size();j++)
            {
                vector<vector<int>> temp;

                if(grid[i][j]==1)
                {
                    dfs(grid, i, j, temp);
                     island.push_back(temp);
                }
            }
        }    

        int islandDist = INT_MAX;

        std::vector<std::vector<int>> firstGroup;
        std::vector<std::vector<int>> secondGroup;
        if (island.size() > 0) 
        {
            firstGroup = island[0];
        }
        if (island.size() > 1) 
        {
            secondGroup = island[1];
        }

        for(int a=0;a<firstGroup.size();a++)
        {
            for(int b=0;b<secondGroup.size();b++)
            {
                int dist = abs(firstGroup[a][0] - secondGroup[b][0]) + abs(firstGroup[a][1] - secondGroup[b][1]) - 1;
                islandDist = std::min(islandDist, dist);
            }
        }

        return islandDist;
    }
};
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