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

January LeetCoding Challenge 31

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 (80 ms)
// Your runtime beats 99.91 % of cpp submissions
// Your memory usage beats 89.86 % of cpp submissions (98.5 MB)