1893. Check if All the Integers in a Range Are Covered

Problem

You are given a 2D integer array ranges and two integers left and right. Each ranges[i] = [starti, endi] represents an inclusive interval between starti and endi.

Return true if each integer in the inclusive range [left, right] **is covered by *at least one* interval in** ranges. Return false otherwise.

An integer x is covered by an interval ranges[i] = [starti, endi] if starti <= x <= endi.

  Example 1:

Input: ranges = [[1,2],[3,4],[5,6]], left = 2, right = 5
Output: true
Explanation: Every integer between 2 and 5 is covered:
- 2 is covered by the first range.
- 3 and 4 are covered by the second range.
- 5 is covered by the third range.

Example 2:

Input: ranges = [[1,10],[10,20]], left = 21, right = 21
Output: false
Explanation: 21 is not covered by any range.

  Constraints:

• 1 <= ranges.length <= 50

• 1 <= starti <= endi <= 50

• 1 <= left <= right <= 50

Solution (Java)

class Solution {
    public boolean isCovered(int[][] ranges, int left, int right) {
        int[] temp = new int[52];
        for (int[] range : ranges) {
            int start = range[0];
            int end = range[ranges[0].length - 1];
            temp[start] += 1;
            temp[end + 1] += -1;
        }
        for (int i = 1; i < temp.length; i++) {
            temp[i] += temp[i - 1];
        }
        for (int i = left; i <= right; i++) {
            if (temp[i] == 0) {
                return false;
            }
        }
        return true;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).