<p>You are given an array of non-overlapping intervals <code>intervals</code> where <code>intervals[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> represent the start and the end of the <code>i<sup>th</sup></code> interval and <code>intervals</code> is sorted in ascending order by <code>start<sub>i</sub></code>. You are also given an interval <code>newInterval = [start, end]</code> that represents the start and end of another interval.</p>

<p>Insert <code>newInterval</code> into <code>intervals</code> such that <code>intervals</code> is still sorted in ascending order by <code>start<sub>i</sub></code> and <code>intervals</code> still does not have any overlapping intervals (merge overlapping intervals if necessary).</p>

<p>Return <code>intervals</code><em> after the insertion</em>.</p>

<p><strong>Note</strong> that you don&#39;t need to modify <code>intervals</code> in-place. You can make a new array and return it.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> intervals = [[1,3],[6,9]], newInterval = [2,5]
<strong>Output:</strong> [[1,5],[6,9]]
</pre>

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

<pre>
<strong>Input:</strong> intervals = [[1,2],[3,5],[6,7],[8,10],[12,16]], newInterval = [4,8]
<strong>Output:</strong> [[1,2],[3,10],[12,16]]
<strong>Explanation:</strong> Because the new interval [4,8] overlaps with [3,5],[6,7],[8,10].
</pre>

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

<ul>
	<li><code>0 &lt;= intervals.length &lt;= 10<sup>4</sup></code></li>
	<li><code>intervals[i].length == 2</code></li>
	<li><code>0 &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
	<li><code>intervals</code> is sorted by <code>start<sub>i</sub></code> in <strong>ascending</strong> order.</li>
	<li><code>newInterval.length == 2</code></li>
	<li><code>0 &lt;= start &lt;= end &lt;= 10<sup>5</sup></code></li>
</ul>

class Solution {
public:
    vector<vector<int>> insert(vector<vector<int>>& intervals, vector<int>& newInterval) {
        int len = static_cast<int>(intervals.size());

        std::vector<std::vector<int>> result;
        bool new_interval_added = false;
        int read_idx = 0;

        // Take all intervals which fall fully before newInterval.
        for(; read_idx < len; read_idx++) {
            if(intervals[read_idx][1] < newInterval[0]) {
                result.push_back(std::move(intervals[read_idx]));
            } else {
                break;
            }
        }

        if(read_idx < len && intervals[read_idx][0] <= newInterval[0]) {
            // The leftmost vertex of newInterval falls inside intervals[read_idx], so merge the two.
            result.push_back(std::move(intervals[read_idx]));
            result.back()[1] = std::max(result.back()[1], newInterval[1]);
            read_idx++;
        } else {
            // The leftmost vertex of newInterval is not inside any other interval, so add just add it
            // as is.
            result.push_back(newInterval);
        }

        // Merge any subsequent interval which intersect the new interval.
        for(; read_idx < len; read_idx++) {
            if(intervals[read_idx][0] > result.back()[1]) {
                break;
            }

            result.back()[1] = std::max(result.back()[1], intervals[read_idx][1]);
        }

        // Copy the remaining intervals as is.
        for(; read_idx < len; read_idx++) {
            result.push_back(std::move(intervals[read_idx]));
        }

        return result;
    }
};
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