README_EN.md

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

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Description

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

Solutions

Interval update using difference array.

Python3

class Solution:
    def isCovered(self, ranges: List[List[int]], left: int, right: int) -> bool:
        diff = [0 for i in range(52)]
        for rg in ranges:
            diff[rg[0]] += 1
            diff[rg[1] + 1] -= 1
        cur = 0
        for i, df in enumerate(diff):
            cur += df
            if left <= i <= right and cur == 0:
                return False
        return True

Java

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

TypeScript

function isCovered(ranges: number[][], left: number, right: number): boolean {
    let diff = new Array(52).fill(0);
    for (let [start, end] of ranges) {
        ++diff[start];
        --diff[end + 1];
    }
    let cur = 0;
    for (let i = 1; i <= 50; i++) {
        cur += diff[i];
        if (i >= left && i <= right && cur <= 0) {
            return false;
        }
    }
    return true;
};

Go

func isCovered(ranges [][]int, left int, right int) bool {
	diff := make([]int, 52)
	for _, rg := range ranges {
		diff[rg[0]]++
		diff[rg[1]+1]--
	}
	cur := 0
	for i, df := range diff {
		cur += df
		if i >= left && i <= right && cur == 0 {
			return false
		}
	}
	return true
}

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