<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>

#include <bits/stdc++.h>
using namespace std;
class Solution {

public:
    vector<vector<bool>> v;
    int m,n;
    map<pair<int, int>, pair<int, int>> ma;

    bool bfs(int i,int j,vector<vector<char>> &g, char c){
        int dx[4] = {1,-1, 0 ,0};
        int dy[4] = {0,0, 1 ,-1};
        deque<pair<int, int>> q;
        q.push_back({i,j});
        v[i][j]=1;
        while(!q.empty()){
          pair<int,int> top = q.front();
          q.pop_front();
          for(int k=0;k<4;k++){
            int x = top.first + dx[k];
            int y = top.second + dy[k];
            if(x<0||x>=m||y<0||y>=n)continue;
            if(v[x][y] && g[x][y]==c && ( ma[{top.first, top.second}].first!=x ||ma[{top.first, top.second}].second!=y )) return true;
            else if(g[x][y]==c && !v[x][y]){
                q.push_back({x,y});
                v[x][y]=true;
                ma[{x,y}] = {top.first, top.second};
            }
          }
        }
        return false;
    }
    bool containsCycle(vector<vector<char>>& grid) {
        m = grid.size();
        n=grid[0].size();
        v= vector<vector<bool>>(m,vector<bool>(n,false));
        if(m==1 || n==1) return false;
        // for(int i=0;i<m;i++){
        //     for(int j=0;j<n;j++){
        //          v[i][j]= false;
        //     }
        // }

        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                 if(!v[i][j]){
                    if(bfs(i,j,grid, grid[i][j])) return true;
                 }
            }
        }

        return false;
    }
};
226269