<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 {
    const long long MOD = 1e9 + 7;

    int findArea(long long width, map<long long, long long> line) {

        long long prev_y = 0;
        long long area = 0;
        long long runningCount = 0;
        for(auto [y, count]: line) {
            
            runningCount += count;
            if(runningCount == count) prev_y = y;

            if(runningCount == 0) {
                area = (area%MOD + ((y - prev_y)%MOD * width%MOD)%MOD)%MOD;
            }

        }
        return area%MOD;
    }

public:
    int rectangleArea(vector<vector<int>>& rectangles) {
        
        vector<vector<long long>> events;
        for(auto rectangle: rectangles) {
            long long x1 = rectangle[0], y1 = rectangle[1], x2 = rectangle[2], y2 = rectangle[3];
            events.push_back({x1, 0, y1, y2});
            events.push_back({x2, 1, y1, y2});
        }

        sort(events.begin(), events.end());

        long long prev_x = 0;
        long long area = 0;
        map<long long, long long> yVals;

        for(auto event: events) {
            
            long long x = event[0], state = event[1], y1 = event[2], y2 = event[3];
            area = (area%MOD + findArea(x - prev_x, yVals)%MOD)%MOD;
            prev_x = x;

            if(state == 1) {
                yVals[y1] -= 1;
                if(yVals[y1] == 0) yVals.erase(y1);
                yVals[y2] += 1;
                if(yVals[y2] == 0) yVals.erase(y2);
            } else {
                yVals[y1] += 1;
                yVals[y2] -= 1;
            }
        }
        return area%MOD;
    }
};
18300