Today I have done leetcode's December LeetCoding Challenge with cpp.

December LeetCoding Challenge 18

Description

Daily Temperatures

Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the ith day to get a warmer temperature. If there is no future day for which this is possible, keep answer[i] == 0 instead.

Example 1:

Input: temperatures = [73,74,75,71,69,72,76,73]
Output: [1,1,4,2,1,1,0,0]

Example 2:

Input: temperatures = [30,40,50,60]
Output: [1,1,1,0]

Example 3:

Input: temperatures = [30,60,90]
Output: [1,1,0]

Constraints:

• 1 <= temperatures.length <= 105
• 30 <= temperatures[i] <= 100

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  vector<int> dailyTemperatures(vector<int>& temperatures) {
    vector<int> monoStack;
    int len = temperatures.size();
    vector<int> answer(len);
    for(int i = len - 1; i >= 0; --i) {
      while(monoStack.size() && temperatures[monoStack.back()] <= temperatures[i]) {
        monoStack.pop_back();
      }
      if(monoStack.size()) answer[i] = monoStack.back() - i;
      monoStack.push_back(i);
    }
    return answer;
  }
};

// Accepted
// 48/48 cases passed (316 ms)
// Your runtime beats 67.33 % of cpp submissions
// Your memory usage beats 89.86 % of cpp submissions (98.5 MB)