LeetCode-739：Daily Temperatures（每日溫度）

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].

思路

使用單調棧解決

Java實現

class Solution {
    public int[] dailyTemperatures(int[] T) {
        int length = T.length;
        Deque<Integer> stack = new ArrayDeque<>(length);
        int[] results = new int[length];
        for (int i = 0; i < length; i++) {
            while (!stack.isEmpty() && T[i] > T[stack.peek()]) {
                int t = stack.poll();
                results[t] = i - t;
            }
            stack.push(i);
        }
        return results;
    }
}

Python實現

from typing import List, Tuple, Dict

class Solution:
    def dailyTemperatures(self, T: List[int]) -> List[int]:
        length = len(T)
        stack = []
        results = [0] * length
        for i in range(length):
            while len(stack) > 0 and T[i] > T[stack[-1]]:
                t = stack.pop()
                results[t] = i - t
            stack.append(i)
        return results

Scala實現

import scala.collection.mutable.Stack

object Solution {
    def dailyTemperatures(T: Array[Int]): Array[Int] = {
        val length = T.length
        val stack = new Stack[Int]()
        val results = new Array[Int](length)
        for (i <- 0 until length) {
            while (!stack.isEmpty && T(i) > T(stack.top)) {
                val t = stack.pop()
                results(t) = i - t;
            }
            stack.push(i)
        }
        results
    }
}