<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:
        bool yes = false;
        int dr[4] { -1, 0, 1, 0 };
	    int dc[4] { 0, 1, 0, -1 };
        int st_inx = 0;
        int count = 0;
        bool validate(int sr , int sc , int n , int m){
            if(sr<0 || sc<0 || sr>=n || sc>=m) return false;
            return true;
        }
        bool isneighbour(vector<vector<char>> &grid , int sr , int sc , int starti , int startj , vector<vector<char>> &grid2 , char current){
            for(int d = 0 ; d < 4 ; d++){
                if(sr+dr[d] == starti && sc+dc[d] == startj) return false;
                if(validate(sr+dr[d] , sc+dc[d] , grid.size() , grid[0].size())
                 && grid2[sr+dr[d]][sc+dc[d]] == '#' && grid[sr+dr[d]][sc+dc[d]] == current) return true;
            }    
            return false;
        }
        void dfs (vector<vector<char>> &grid , int sr , int sc , int st_inx , char current , int starti , int startj , vector<vector<char>> &grid2){
            if(!validate(sr,sc,grid.size(),grid[0].size()) || grid[sr][sc] != current || yes || grid2[sr][sc] == '#') return;
            if(isneighbour(grid , sr , sc , starti , startj , grid2 , current)){
                yes = true;
                return;
            }
            grid2[sr][sc] = '#';
            for(int d = 0 ; d < 4 ; d++){
                dfs(grid , sr+dr[st_inx] , sc+dc[st_inx] , st_inx , current , sr , sc , grid2);
                st_inx = (st_inx+1)%4; 
            }
        }  
        bool containsCycle(vector<vector<char>>& grid) {
            vector<vector<char>> grid2 = grid;
            for(int i = 0 ; i < grid.size() ; i++){
                for(int j = 0 ; j < grid[0].size() ; j++){
                    yes = false;
                    if(grid2[i][j] != '#') dfs(grid , i , j , 0 , grid[i][j] , i ,j , grid2);
                    if(yes) return true;
                }
            }
            return false;
        }
};
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