Merge Two Sorted Interval Arrays

Problem You are given two interval arrays A and B, each sorted by start. Each interval is a closed interval [l, r]. Merge the two lists and return the union of all intervals (merge any overlapping intervals). The output must be sorted by start. Input First line: m Next m lines: l r for intervals in A Next line: n Next n lines: l r for intervals in B Output Print merged intervals, one per line as l r. Constraints 0 <= m, n <= 2e5 -1e9 <= l <= r <= 1e9 Example A = [[1,2],[3,4]], B = [[1,3],[7,8],[9,10]] => [[1,4],[7,8],[9,10]] Example Input 2 1 2 3 4 3 1 3 7 8 9 10 Output 1 4 7 8 9 10