kango.swift

import Foundation

// Complete the kangaroo function below.
func kangaroo(x1: Int, v1: Int, x2: Int, v2: Int) -> String {
    if v2 >= v1 {
        return "NO"
    }
    let speedDifference = v1 - v2
    let initialPositionDifference = x2 - x1

    if (initialPositionDifference % speedDifference) == 0 {
        return "YES"
    } else {
        return "NO"
    }
}