Merging Overlapping Intervals

Given a set of intervals, print all non-overlapping intervals after merging overlapping intervals.


For example,

Input:  {1, 5}, {2, 3}, {4, 6}, {7, 8}, {8, 10}, {12, 15}

Intervals after merging overlapping intervals are {1, 6}, {7, 10}, {12, 15}.

The idea is to sort the intervals in increasing order of their starting time. Then for each interval,

  • If stack is empty or top interval in the stack do not overlap with current interval, we push it to the stack.
  • If top interval of stack overlap with current interval, we merge two intervals by updating ending of top interval to ending of current interval.

Finally, we print all non-overlapping intervals present in the stack.

C++ implementation –

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(12, 15)
(7, 10)
(1, 6)

The time complexity of above solution is O(nlogn) and auxiliary space used by the program is O(n).

Thanks for reading.

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Vinayak Sangar
Vinayak Sangar
This problem can be solved in O(nlog n) time and O(1) space as Take two arrays arr1[] array storing the starting index of all the intervals arr2[] array storing the ending indexes of all intervals Now sort both the arrays in ascending order Now every time the number of guests… Read more »