Time Cost

8min0s

Implementation

The solution’s time complexity is n*log(n). Some boundaries should be noticed such as “hour_needed” could be over maximum integer.

Code

• My Solution

  class Solution {
  public:
    vector<int> nextGreaterElement(vector<int>& nums1, vector<int>& nums2) {
        vector<int> result(nums1.size(), -1);
        unordered_map<int, int> nextgreat;
        stack<int> st;
  
        int tmp = 0;
  
        for (int num: nums2) {
            while (!st.empty()) {
                tmp = st.top();
                if (tmp < num) {
                    nextgreat.emplace(tmp, num);
                    st.pop();
                }else {
                    break;
                }
            }
            st.push(num);
        }
  
        for (int i=0; i<nums1.size(); i++) {
            if (nextgreat.count(nums1[i])) {
                result[i] = nextgreat[nums1[i]];
            }
        }
  
        return result;
    }
  };