739. Daily Temperatures

#### QUESTION:

Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the ith day to get a warmer temperature. If there is no future day for which this is possible, keep answer[i] == 0 instead.

Example 1:

``````Input: temperatures = [73,74,75,71,69,72,76,73]
Output: [1,1,4,2,1,1,0,0]
``````

Example 2:

``````Input: temperatures = [30,40,50,60]
Output: [1,1,1,0]
``````

Example 3:

``````Input: temperatures = [30,60,90]
Output: [1,1,0]
``````

Constraints:

``````1 <= temperatures.length <= 105
30 <= temperatures[i] <= 100
``````

#### SOLUTION:

``````class Solution {
func dailyTemperatures(_ temperatures: [Int]) -> [Int] {
var arr: [Int] = Array(repeating: 0, count: temperatures.count)
var stack: [Int] = []
if temperatures.count < 2 {
return arr
}
for i in 0..<temperatures.count {
while !stack.isEmpty && temperatures[i] > temperatures[stack.last!] {
let index = stack.removeLast()
arr[index] = i - index
}
stack.append(i)
}
return arr
}
}
``````