749.Daily Temperatures

Tags: Medium Stack Array

Links: https://leetcode.com/problems/daily-temperatures/

---

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:
    vector<int> dailyTemperatures(vector<int>& T) {
        std::ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout.tie(NULL);

        int n = T.size();
        vector<int> res(n, 0);
        stack<int> s; s.push(0);
        for (int i = 1; i < n; ++i) {
            if (s.empty()) s.push(i);
            else {
                while (!s.empty() && T[i] > T[s.top()]) {
                    res[s.top()] = i - s.top(); s.pop();
                }
                s.push(i);
            }
        }

        return res;
    }
};

单调栈的模板题，注意一下，是记录**经过几天**超过当前值，而不是第一个大于当前值的位置。