10.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].

Solution: (Finding the next greater element)

class Solution
{
public:
    vector<int> dailyTemperatures(vector<int> &t)
    {
    
        stack<int> s;
        vector<int> v(t.size(), 0);
        for (int i = 0; i < t.size(); i++)
        {
            while (!s.empty() && t[i] > t[s.top()])
            {
                v[s.top()] = i - s.top();
                s.pop();
            }

            s.push(i);
        }
        return v;
    }
};

Time Complexity: O(N)