<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>

#define ll long long 
ll mod = 1e9+7;

class Solution {
public:
    int rectangleArea(vector<vector<int>>& rectangles) {
        int n = rectangles.size();
        int m = rectangles[0].size();
        vector<vector<int>>graph(2*n+1,vector<int>(2*n+1,0));
        set<int>ux, uy;
        for(auto i: rectangles) {
            ux.insert(i[0]);
            ux.insert(i[2]);
            uy.insert(i[1]);
            uy.insert(i[3]);
        }
        map<int,int>x, y;
        vector<ll>ix(2*n+1), iy(2*n+1);
        int idx = 0;
        for(auto i: ux) {
            x[i] = idx;
            ix[idx] = i; 
            idx++;
        }
        idx = 0;
        for(auto i: uy) {
            y[i] = idx;
            iy[idx] = i;
            idx++;
        }

        for(auto i: rectangles) {
            int x1 = x[i[0]];
            int x2 = x[i[2]];
            int y1 = y[i[1]];
            int y2 = y[i[3]];
            for(int j=x1; j<x2; j++) {
                for(int k=y1; k<y2; k++) {
                    graph[j][k] = 1;
                }
            }
        }
        ll ans = 0;
        for(int j=0; j<2*n; j++) {
            for(int k=0; k<2*n; k++) {
                if(graph[j][k] == 1) {
                    ans = (ans + (ix[j+1]-ix[j])*(iy[k+1]-iy[k]))%mod;
                }
            }
        }
        return ans;
    }
};
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