<p>Given a <code>rows x cols</code>&nbsp;binary <code>matrix</code> filled with <code>0</code>&#39;s and <code>1</code>&#39;s, find the largest rectangle containing only <code>1</code>&#39;s and return <em>its area</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/14/maximal.jpg" style="width: 402px; height: 322px;" />
<pre>
<strong>Input:</strong> matrix = [[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;]]
<strong>Output:</strong> 6
<strong>Explanation:</strong> The maximal rectangle is shown in the above picture.
</pre>

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

<pre>
<strong>Input:</strong> matrix = [[&quot;0&quot;]]
<strong>Output:</strong> 0
</pre>

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

<pre>
<strong>Input:</strong> matrix = [[&quot;1&quot;]]
<strong>Output:</strong> 1
</pre>

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

<ul>
	<li><code>rows == matrix.length</code></li>
	<li><code>cols == matrix[i].length</code></li>
	<li><code>1 &lt;= row, cols &lt;= 200</code></li>
	<li><code>matrix[i][j]</code> is <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
</ul>

class Solution {
public:
int solve(vector<int>& A){
    int ans=0;
    int n=A.size();
    for(int i=0;i<A.size();i++){
        int r=i+1,l=i-1;
        while(r<A.size()&&A[r]>=A[i]){
            r++;
        }
        while(l>=0&&A[l]>=A[i]){
            l--;
        }
        cout<<r<<' '<<l<<' '<<A[i]<<endl;
        ans=max(ans,A[i]*(r-l-1));
    }
    cout<<endl;
    return ans;
}
    int maximalRectangle(vector<vector<char>>& matrix) {
        int n=matrix.size();
        int m=matrix[0].size();
        vector<vector<int>>one(n,vector<int>(m));
        for(int j=0;j<m;j++){
            for(int i=0;i<n;i++){
                if(i==0){
                    one[i][j]=matrix[i][j]-48;
                }
              else {
                    if(matrix[i][j]=='1')
                    one[i][j]=one[i-1][j]+1; 
                    else one[i][j]=0;  
              }
            }
        }
        int ans=0;
        for(int i=0;i<n;i++){
            cout<<i<<' ';
            ans=max(ans,solve(one[i]));
        }
        return ans;
    }
};
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