<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:
vector<int> rs(vector<int>& ar){
    stack<int>st;
    vector<int>vr;
    int l=ar.size();
    for(int i=l-1;i>=0;i--){
        while(!st.empty()&&ar[st.top()]>=ar[i]){
            st.pop();
        }
        if(st.empty()){
            vr.push_back(l);
        }else{
            vr.push_back(st.top());
        }
        st.push(i);
    }
    reverse(vr.begin(),vr.end());
    return vr;
}
vector<int> ls(vector<int>& ar){
    stack<int>st;
    vector<int>vl;
    int l=ar.size();
    for(int i=0;i<l;i++){
        while(!st.empty()&&ar[st.top()]>=ar[i]){
            st.pop();
        }if(st.empty()){
            vl.push_back(-1);
        }else{
            vl.push_back(st.top());
        }
        st.push(i);
    }
    return vl;
}
int MAH(vector<int>& ar){
    vector<int>right=rs(ar);
    vector<int>left=ls(ar);
    int max=0,l=ar.size();
    for(int i=0;i<l;i++){
        int area=ar[i]*(right[i]-left[i]-1);
        if(area>max){
            max=area;
        }
    }
    return max;
}
int maximalRectangle(vector<vector<char>>& ar) {
        vector<int> v(ar[0].size(),0);
    int l=ar.size();
    int mx=0;
    for(int i=0;i<l;i++){
        for(int j=0;j<v.size();j++){
            if(ar[i][j]=='0'){
                v[j]=0;
            }else{
                v[j]++;
            }
        }
        mx=max(mx,MAH(v));
    }
    return mx;
    }
};
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