class Solution {
public:vector<int> dailyTemperatures(vector<int>& temperatures) {stack<int> st;vector<int> result(temperatures.size(), 0);for(int i = 0; i < temperatures.size(); i++){while(!st.empty() && temperatures[i] > temperatures[st.top()]){result[st.top()] = i - st.top();st.pop();}st.push(i);}return result;}
};

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