739 Daily Temperatures

1. Question

Given a list of dailytemperatures, produce a list 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, put0instead.
For example, given the listtemperatures = [73, 74, 75, 71, 69, 72, 76, 73], your output should be[1, 1, 4, 2, 1, 1, 0, 0].
Note:The length oftemperatureswill be in the range[1, 30000]. Each temperature will be an integer in the range[30, 100].

2. Implementation

(1) Monotone Stack
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class Solution {
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public int[] dailyTemperatures(int[] temperatures) {
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int n = temperatures.length;
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int[] res = new int[n];
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Stack<Integer> stack = new Stack<>();
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for (int i = 0; i < n; i++) {
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int curTemp = temperatures[i];
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while (!stack.isEmpty() && curTemp > temperatures[stack.peek()]) {
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res[stack.peek()] = i - stack.peek();
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stack.pop();
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}
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stack.push(i);
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}
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return res;
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}
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}
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3. Time & Space Complexity

Monotone Stack: 时间复杂度O(n), 空间复杂度O(n)