diff --git a/Stack/496.Next-Greater-Element-I/496.Next Greater Element I.cpp b/Stack/496.Next-Greater-Element-I/496.Next Greater Element I.cpp
deleted file mode 100644
index b976c0380..000000000
--- a/Stack/496.Next-Greater-Element-I/496.Next Greater Element I.cpp	
+++ /dev/null
@@ -1,29 +0,0 @@
-class Solution {
-public:
-    vector<int> nextGreaterElement(vector<int>& findNums, vector<int>& nums) 
-    {
-        stack<int>Stack;
-        unordered_map<int,int>Map;
-        
-        for (int i=0; i<nums.size(); i++)
-        {
-            while (!Stack.empty() && Stack.top()<nums[i])
-            {
-                Map[Stack.top()]=nums[i];
-                Stack.pop();
-            }                            
-            Stack.push(nums[i]);
-        }
-        
-        vector<int>results;
-        for (int i=0; i<findNums.size(); i++)
-        {
-            if (Map.find(findNums[i])==Map.end())
-                results.push_back(-1);
-            else
-                results.push_back(Map[findNums[i]]);
-        }
-        
-        return results;
-    }
-};
diff --git a/Stack/496.Next-Greater-Element-I/496.Next-Greater-Element-I.cpp b/Stack/496.Next-Greater-Element-I/496.Next-Greater-Element-I.cpp
new file mode 100644
index 000000000..defe96c1a
--- /dev/null
+++ b/Stack/496.Next-Greater-Element-I/496.Next-Greater-Element-I.cpp
@@ -0,0 +1,28 @@
+class Solution {
+    unordered_map<int,int>nextGreater;
+public:
+    vector<int> nextGreaterElement(vector<int>& nums1, vector<int>& nums2) 
+    {
+        int n = nums2.size();
+        stack<int>Stack;  // index
+        for (int i = 0; i < n; i++)
+        {
+            while (!Stack.empty() && nums2[Stack.top()] < nums2[i])
+            {
+                nextGreater[nums2[Stack.top()]] = nums2[i];
+                Stack.pop();
+            }
+            Stack.push(i);
+        }
+        
+        vector<int>rets;
+        for (int x: nums1)
+        {
+            if (nextGreater.find(x)==nextGreater.end())
+                rets.push_back(-1);
+            else
+                rets.push_back(nextGreater[x]);
+        }
+        return rets;        
+    }
+};