Update

problems/0084.柱状图中最大的矩形.md

@@ -0,0 +1,31 @@
+
+# 链接 
+
+https://leetcode-cn.com/problems/largest-rectangle-in-histogram/ 
+
+## 思路
+
+```
+class Solution {
+public:
+    int largestRectangleArea(vector<int>& heights) {
+        int sum = 0;
+        for (int i = 0; i < heights.size(); i++) {
+            int left = i;
+            int right = i;
+            for (; left >= 0; left--) {
+                if (heights[left] < heights[i]) break;
+            }
+            for (; right < heights.size(); right++) {
+                if (heights[right] < heights[i]) break;
+            }
+            int w = right - left - 1;
+            int h = heights[i];
+            sum = max(sum, w * h);
+        }
+        return sum;
+    }
+};
+```
+
+如上代码并不能通过leetcode，超时了，因为时间复杂度是O(n^2)。