diff --git a/src/main/java/com/cool/hot100/stack/Num84.java b/src/main/java/com/cool/hot100/stack/Num84.java
new file mode 100644
index 0000000..554ca98
--- /dev/null
+++ b/src/main/java/com/cool/hot100/stack/Num84.java
@@ -0,0 +1,36 @@
+package com.cool.hot100.stack;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/18/14:20
+ * DayNumber 1
+ * Hard 3
+ * Level ?
+ */
+public class Num84 {
+
+    public int largestRectangleArea(int[] heights) {
+        Deque<Integer> deque=new LinkedList<>();
+        int res=0;
+        deque.offerLast(0);
+        int[] newHeights=new int[heights.length+2];
+        System.arraycopy(heights, 0, newHeights, 1, heights.length);
+        heights=newHeights;
+        for(int i=0;i<heights.length;i++){
+            while(!deque.isEmpty()&&heights[deque.peekLast()]>heights[i]){
+                // 出栈
+                int cur=deque.pollLast();
+                int left=deque.peekLast()+1;
+                res=Math.max(res,(i-left)*heights[cur]);
+            }
+            deque.offerLast(i);
+        }
+        return res;
+    }
+
+}