# Count Integers in Intervals solution leetcode

## Count Integers in Intervals solution leetcode

Given an empty set of intervals, implement a data structure that can:

• Add an interval to the set of intervals.
• Count the number of integers that are present in at least one interval.

Implement the `CountIntervals` class:

• `CountIntervals()` Initializes the object with an empty set of intervals.
• `void add(int left, int right)` Adds the interval `[left, right]` to the set of intervals.
• `int count()` Returns the number of integers that are present in at least one interval.

Note that an interval `[left, right]` denotes all the integers `x` where `left <= x <= right`.

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## Count Integers in Intervals solution leetcode

```Input
[[], [2, 3], [7, 10], [], [5, 8], []]
Output
[null, null, null, 6, null, 8]

Explanation
CountIntervals countIntervals = new CountIntervals(); // initialize the object with an empty set of intervals.
countIntervals.count();    // return 6
// the integers 2 and 3 are present in the interval [2, 3].
// the integers 7, 8, 9, and 10 are present in the interval [7, 10].
countIntervals.count();    // return 8
// the integers 2 and 3 are present in the interval [2, 3].
// the integers 5 and 6 are present in the interval [5, 8].
// the integers 7 and 8 are present in the intervals [5, 8] and [7, 10].
// the integers 9 and 10 are present in the interval [7, 10].
```

Constraints:

## Count Integers in Intervals solution leetcode

• `1 <= left <= right <= 109`
• At most `105` calls in total will be made to `add` and `count`.
• At least one call will be made to `count`.