diff --git a/C++/084. Largest Rectangle in Histogram.cpp b/C++/084. Largest Rectangle in Histogram.cpp
new file mode 100644
index 0000000..72b8300
--- /dev/null
+++ b/C++/084. Largest Rectangle in Histogram.cpp	
@@ -0,0 +1,22 @@
+class Solution {
+public:
+    int largestRectangleArea(vector<int>& heights) {    //Monotone Stack
+        if (heights.empty())
+            return 0;
+        heights.push_back(-1);
+        stack<int> stk;
+        int ans = 0;
+        for (int i = 0; i < heights.size(); ++i){
+            while (stk.size() && heights[stk.top()] > heights[i]){
+                int cur = stk.top();
+                stk.pop();
+                if (stk.empty())
+                    ans = max(ans, heights[cur] * i);
+                else
+                    ans = max(ans, heights[cur] * (i - stk.top() - 1));
+            }
+            stk.push(i);
+        }
+        return ans;
+    }
+};
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