leetcode

0 class Solution {

1 public:

2 vector<int> nextGreaterElement(vector<int> &nums1, vector<int> &nums2) {

3 vector<int> res(nums1.size(), -1);

4 unordered_map<int, int> um;

5 stack<int> st;

6

7 for (int i = 0; i < nums2.size(); i++) {

8 while (!st.empty() && nums2[i] > st.top()) {

9 um.insert(make_pair(st.top(), nums2[i]));

10 st.pop();

11 }

12 st.push(nums2[i]);

13 }

14

15 for (int i = 0; i < nums1.size(); i++)

16 if (um.find(nums1[i]) != um.end()) res[i] = um[nums1[i]];

17

18 return res;

19 }

20 };