739.daily-temperatures.java

/*
 * @lc app=leetcode id=739 lang=java
 *
 * [739] Daily Temperatures
 *
 * https://leetcode.com/problems/daily-temperatures/description/
 *
 * algorithms
 * Medium (59.10%)
 * Total Accepted:    53.6K
 * Total Submissions: 90.3K
 * Testcase Example:  '[73,74,75,71,69,72,76,73]'
 *
 *
 * Given a list of daily temperatures T, return a list such that, for each day
 * in the input, tells you how many days you would have to wait until a warmer
 * temperature.  If there is no future day for which this is possible, put 0
 * instead.
 *
 * For example, given the list of temperatures T = [73, 74, 75, 71, 69, 72, 76,
 * 73], your output should be [1, 1, 4, 2, 1, 1, 0, 0].
 *
 *
 * Note:
 * The length of temperatures will be in the range [1, 30000].
 * Each temperature will be an integer in the range [30, 100].
 *
 */
class Solution {
  public int[] dailyTemperatures(int[] T) {
    Stack<Integer> stack = new Stack<>();
    int[] ret = new int[T.length];
    for (int i = 0; i < T.length; i++) {
      while(!stack.empty() && T[i] > T[stack.peek()]) {
        int index = stack.pop();
        ret[index] = i - index;
      }
      stack.push(i);
    }
    return ret;
  }
}