739. Daily Temperatures #

Problem Statement: #

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: #

public int[] dailyTemperatures(int[] temp) {
  int n = temp.length;
  int[] days = new int[n];
  Stack<Integer> stk = new Stack<>();
  for (int i = n - 1; i >= 0; i--) {
    while (!stk.isEmpty() && temp[stk.peek()] <= temp[i])
      stk.pop();

    if (!stk.isEmpty())
      days[i] = stk.peek() - i;

    stk.push(i);
  }
  return days;
}

... #