add longest turbulent subarray solution

Author: lazybing

C++/leetcode978_longest_turbulent_subarray/maxturbulencesize.cpp

@@ -0,0 +1,19 @@
+class Solution {
+public:
+    int maxTurbulenceSize(vector<int>& A) {
+        int res = 0, clen = 0;
+
+        for (int i = 0; i < A.size(); i++) {
+            if (i >= 2 &&
+                ((A[i - 2] > A[i - 1] && A[i - 1] < A[i]) || (A[i - 2] < A[i -1] && A[i - 1] > A[i]))) {
+                clen++;
+            } else if (i >= 1 && A[i - 1] != A[i]) {
+                clen = 2;
+            } else {
+                clen = 1;
+            }
+            res = max(res, clen);
+        }
+        return res;
+    }
+};