<p>Given a 2D array of characters <code>grid</code> of size <code>m x n</code>, you need to find if there exists any cycle consisting of the <strong>same value</strong> in <code>grid</code>.</p>

<p>A cycle is a path of <strong>length 4 or more</strong> in the grid that starts and ends at the same cell. From a given cell, you can move to one of the cells adjacent to it - in one of the four directions (up, down, left, or right), if it has the <strong>same value</strong> of the current cell.</p>

<p>Also, you cannot move to the cell that you visited in your last move. For example, the cycle <code>(1, 1) -&gt; (1, 2) -&gt; (1, 1)</code> is invalid because from <code>(1, 2)</code> we visited <code>(1, 1)</code> which was the last visited cell.</p>

<p>Return <code>true</code> if any cycle of the same value exists in <code>grid</code>, otherwise, return <code>false</code>.</p>

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

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/1.png" style="width: 231px; height: 152px;" /></strong></p>

<pre>
<strong>Input:</strong> grid = [[&quot;a&quot;,&quot;a&quot;,&quot;a&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;b&quot;,&quot;b&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;b&quot;,&quot;b&quot;,&quot;a&quot;],[&quot;a&quot;,&quot;a&quot;,&quot;a&quot;,&quot;a&quot;]]
<strong>Output:</strong> true
<strong>Explanation: </strong>There are two valid cycles shown in different colors in the image below:
<img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/11.png" style="width: 225px; height: 163px;" />
</pre>

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

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/22.png" style="width: 236px; height: 154px;" /></strong></p>

<pre>
<strong>Input:</strong> grid = [[&quot;c&quot;,&quot;c&quot;,&quot;c&quot;,&quot;a&quot;],[&quot;c&quot;,&quot;d&quot;,&quot;c&quot;,&quot;c&quot;],[&quot;c&quot;,&quot;c&quot;,&quot;e&quot;,&quot;c&quot;],[&quot;f&quot;,&quot;c&quot;,&quot;c&quot;,&quot;c&quot;]]
<strong>Output:</strong> true
<strong>Explanation: </strong>There is only one valid cycle highlighted in the image below:
<img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/2.png" style="width: 229px; height: 157px;" />
</pre>

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

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2020/07/15/3.png" style="width: 183px; height: 120px;" /></strong></p>

<pre>
<strong>Input:</strong> grid = [[&quot;a&quot;,&quot;b&quot;,&quot;b&quot;],[&quot;b&quot;,&quot;z&quot;,&quot;b&quot;],[&quot;b&quot;,&quot;b&quot;,&quot;a&quot;]]
<strong>Output:</strong> false
</pre>

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

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 500</code></li>
	<li><code>grid</code> consists only of lowercase English letters.</li>
</ul>

class Solution {
public:
    int dx[4] = {-1,1,0,0};
    int dy[4] = {0,0,-1,1};

    bool isValid(int row, int col, int totalRows, int totalCols){
          return row >= 0 && row < totalRows && col >= 0 && col < totalCols; 
    }


    bool dfs(int currRow, int currCol, vector<vector<bool>> &visited,vector<vector<char>> &grid, int parentRow, int parentCol) {
       if(visited[currRow][currCol] && !( currRow == parentRow && currCol == parentCol)){
          return true;
       }

       visited[currRow][currCol] = true;
       
       bool ans = false;
       
       for(int i=0;i<4;i++) {
         int neighx = currRow + dx[i];
         int neighy = currCol + dy[i];
         if(isValid(neighx, neighy, grid.size(), grid[0].size()) 
         && grid[neighx][neighy] == grid[currRow][currCol] ) {
            if(visited[neighx][neighy] && !(neighx == parentRow && neighy == parentCol)){ 
              return true;
            } else {
               if(!visited[neighx][neighy]) {
                 ans = ans || dfs(neighx, neighy, visited, grid, currRow, currCol);
               }
            }
           
         }
       }

       return ans;

    }

    bool containsCycle(vector<vector<char>>& grid) {
         bool ans = false;
         vector<bool> alphabets(26, false);
         int x = 0;
          vector<vector<bool>> visited(grid.size(), vector<bool>(grid[0].size(), false));
        for(int i=0;i<grid.size() ; i++) {
            for(int j=0;j<grid[i].size();j++) {
            
                    if(!visited[i][j]){
                        ans = ans || dfs(i,j,visited,grid, -1,-1);
                    }
        }
    }
       return ans;
    }
};
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