Question

How to detect whether any intervals overlap in a list of start and end times with Swift

Answer 1

import Foundation

func hasOverlap(_ intervals: [(Int, Int)]) -> Bool {
    if intervals.isEmpty {
        return true
    }

    // Sorting is essential because once intervals are ordered by 
    // start time, any overlap can only occur between adjacent intervals.
    let sorted = intervals.sorted { $0.0 < $1.0 }
    // (5,9), (11,12), (15,17)

    // (5,9) and (11,12) → 11 < 9? No
    // (11,12) and (15,17) → 15 < 12? No

    // The loop compares each interval with the one before it.
    for i in 1..<sorted.count {
        if sorted[i].0 < sorted[i - 1].1 {
            return false // Overlap found
        }
    }

    return true // No overlap
}

func main() {
    let intervals: [(Int, Int)] = [
        (11, 12),
        (5, 9),
        (15, 17)
    ]

    if hasOverlap(intervals) {
        print("There are NO overlapping intervals")
    } else {
        print("There ARE overlapping intervals")
    }
}

main()



/*
run:

There are NO overlapping intervals

*/

 

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