https://leetcode.com/problems/next-greater-element-ii/description/

class Solution {public:    vector
     
       nextGreaterElements(vector
      
       & nums) {        stack
       
         st;        int n = nums.size();        for (int i = 2 * n - 1; i >= n; i--) {            int cur = nums[i % n];            while (!st.empty() && cur >= st.top())                st.pop();            st.push(cur);        }                vector
        
          res(n, 0);        for (int i = n - 1; i >= 0; i--) {            int cur = nums[i];            while (!st.empty() && cur >= st.top())                st.pop();            if (st.empty())                res[i] = -1;            else                res[i] = st.top();            st.push(cur);        }                return res;    }};