import Foundation
// Print all elements in an array
func printArray(_ arr: [Int]) {
print(arr.map { String($0) }.joined(separator: " "))
}
// Calculate how many days you must wait for a warmer temperature
func numberOfDaysToWait(_ temperatures: [Int]) -> [Int] {
let size = temperatures.count
var result = Array(repeating: 0, count: size)
var stack: [Int] = [] // stack of indices
for i in 0..<size {
// While the current temperature is warmer than the temperature
// at the index stored at the top of the stack:
while let last = stack.last, temperatures[i] > temperatures[last] {
let idx = stack.removeLast()
result[idx] = i - idx
}
// Push the current index onto the stack
stack.append(i)
}
// Remaining indices in the stack have no warmer future day
// (result already contains zeros)
return result
}
// Example usage:
let temperatures = [82, 84, 81, 58, 85, 89, 75, 71]
// 82 -> 84 = 1
// 84 -> 81 -> 58 -> 85 = 3
// 81 -> 58 -> 85 = 2
// 58 -> 85 = 1
// 85 -> 89 = 1
// 89 -> 75 -> 71 = 0
// 75 -> 71 = 0
let result = numberOfDaysToWait(temperatures)
printArray(result)
/*
run:
1 3 2 1 1 0 0 0
*/
