<p>You are given a 2D array of axis-aligned <code>rectangles</code>. Each <code>rectangle[i] = [x<sub>i1</sub>, y<sub>i1</sub>, x<sub>i2</sub>, y<sub>i2</sub>]</code> denotes the <code>i<sup>th</sup></code> rectangle where <code>(x<sub>i1</sub>, y<sub>i1</sub>)</code> are the coordinates of the <strong>bottom-left corner</strong>, and <code>(x<sub>i2</sub>, y<sub>i2</sub>)</code> are the coordinates of the <strong>top-right corner</strong>.</p>

<p>Calculate the <strong>total area</strong> covered by all <code>rectangles</code> in the plane. Any area covered by two or more rectangles should only be counted <strong>once</strong>.</p>

<p>Return <em>the <strong>total area</strong></em>. Since the answer may be too large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/06/06/rectangle_area_ii_pic.png" style="width: 600px; height: 450px;" />
<pre>
<strong>Input:</strong> rectangles = [[0,0,2,2],[1,0,2,3],[1,0,3,1]]
<strong>Output:</strong> 6
<strong>Explanation:</strong> A total area of 6 is covered by all three rectangles, as illustrated in the picture.
From (1,1) to (2,2), the green and red rectangles overlap.
From (1,0) to (2,3), all three rectangles overlap.
</pre>

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

<pre>
<strong>Input:</strong> rectangles = [[0,0,1000000000,1000000000]]
<strong>Output:</strong> 49
<strong>Explanation:</strong> The answer is 10<sup>18</sup> modulo (10<sup>9</sup> + 7), which is 49.
</pre>

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

<ul>
	<li><code>1 &lt;= rectangles.length &lt;= 200</code></li>
	<li><code>rectanges[i].length == 4</code></li>
	<li><code>0 &lt;= x<sub>i1</sub>, y<sub>i1</sub>, x<sub>i2</sub>, y<sub>i2</sub> &lt;= 10<sup>9</sup></code></li>
	<li><code>x<sub>i1 &lt;= </sub>x<sub>i2</sub></code></li>
	<li><code>y<sub>i1 &lt;=</sub> y<sub>i2</sub></code></li>
</ul>

class Solution {
public:
    int rectangleArea(vector<vector<int>>& rectangles) {
        set<int> x,y;
        for(auto rec:rectangles){
            x.insert(rec[0]);
            x.insert(rec[2]);
            y.insert(rec[1]);
            y.insert(rec[3]);
        }
        int n=x.size(),m=y.size();
        vector<int> iXv,iYv;
        for(auto i:x) iXv.push_back(i);
        for(auto i:y) iYv.push_back(i);
        unordered_map<int,int> idxMapy,idxMapx;
        for(int i=0;i<n;i++) idxMapx[iXv[i]]=i;
        for(int i=0;i<m;i++) idxMapy[iYv[i]]=i;

        vector<vector<bool>>grid(n,vector<bool>(m));

        long long ans=0;
        const int MOD=1e9+7;

        // mark rectangles
        for(auto rec:rectangles){
            for(int i=idxMapx[rec[0]];i<idxMapx[rec[2]];i++){
                for(int j=idxMapy[rec[1]];j<idxMapy[rec[3]];j++){
                    grid[i][j]=true;
                }
            }
        }
        // calc answer 
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(grid[i][j]){
                    ans=(ans+1LL*(iXv[i+1]-iXv[i])*(iYv[j+1]-iYv[j]))%MOD;
                }
            }
        }
        return ans;

    }
};
14100