Create longest-mountain-in-array.cpp

Author: kamyu104

C++/longest-mountain-in-array.cpp

@@ -0,0 +1,21 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int longestMountain(vector<int>& A) {
+        int result = 0, up_len = 0, down_len = 0;
+        for (int i = 1; i < A.size(); ++i) {
+            if ((down_len && A[i - 1] < A[i]) ||
+                A[i - 1] == A[i]) {
+                up_len = down_len = 0;
+            }
+            up_len += A[i - 1] < A[i];
+            down_len += A[i - 1] > A[i];
+            if (up_len && down_len) {
+                result= max(result, up_len + down_len + 1);
+            }
+        }
+        return result;
+    }
+};