LeetCode [739] 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].

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class Solution { stack<int> stk;//index of decreasing temp public: vector<int> dailyTemperatures(vector<int>& T) { vector<int> ret(T.size()); for(int i=0; i<T.size(); ++i){ if(stk.empty()) stk.push(i); else{ if(T[stk.top()]>=T[i]) stk.push(i); else{ while(!stk.empty() && T[stk.top()]<T[i]){ int t = stk.top(); stk.pop(); ret[t] = i-t; } stk.push(i); } } } while(!stk.empty()){ ret[stk.top()] = 0; stk.pop(); } return ret; } };