<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:
    #define ll long long
    ll MOD=1e9+7;
    static bool cmp(vector<int>&v1,vector<int>&v2){
        if(v1[0]==v2[0]){
            return v1[2]<v2[2];
        }
        return v1[0]<v2[0];
    }
    int rectangleArea(vector<vector<int>>& rectangles) {
        ll n=rectangles.size(),answer=0;
        set<ll>ss;
        for(auto &x:rectangles){
            ss.insert(x[1]);ss.insert(x[3]);
        }
        sort(rectangles.begin(),rectangles.end(),cmp);
        ll lower=*ss.begin();
        for(auto &x:ss){
            ll upper=x;
            ll height=upper-lower;
            ll left=rectangles[0][0],right=left;
            for(auto &y:rectangles){
                if(y[1]<=lower && y[3]>=upper){
                    if(y[0]>right){
                        answer=(answer+height*(right-left))%MOD;
                        left=y[0];
                    }
                    if(y[2]>right){
                        right=y[2];
                    }
                }
            }
            answer=(answer+height*(right-left))%MOD;
            lower=upper;
        }
        return answer%MOD;
    }
};
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