<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:
    long long int M = 1000000007;
    long long int getYAxisCovered(map<long long int,long long int>& ySweep){
        long long int length = 0, count = 0, last = -1;
        for(auto it = ySweep.begin();it!=ySweep.end();++it){
            if(count == 0){
                last = it->first;
            }
            count += it->second;
            if(count==0){
                length += it->first - last;
            }
        }
        return length;
    } 
    int rectangleArea(vector<vector<int>>& rect) {
        int n = rect.size();
        sort(rect.begin(), rect.end());
        map<long long int,long long int> xSweep;
        long long int area = 0;
        int index = 0;
        while(index<n){
            xSweep[rect[index][0]]++;
            xSweep[rect[index][2]]--;
            index++;
        }
        auto prev = xSweep.begin();
        for(auto it = xSweep.begin(); it != xSweep.end(); ++it){
            if(it!=xSweep.begin()){
                long long int right = it->first;
                long long int left = prev->first;
                map<long long int,long long int> ySweep;
                for(int i=0;i<n;++i){
                    if(rect[i][0]<=left&&rect[i][2]>=right){
                        ySweep[rect[i][1]]++;
                        ySweep[rect[i][3]]--;
                    }
                }
                area += getYAxisCovered(ySweep)*(right-left);
            }
            prev = it;
        }
        return area%M;
    }
};
18100