Create count-hills-and-valleys-in-an-array.cpp

Author: kamyu104

C++/count-hills-and-valleys-in-an-array.cpp

@@ -0,0 +1,20 @@
+// Time:  O(n)
+// Space: O(1)
+
+// simulation, array
+class Solution {
+public:
+    int countHillValley(vector<int>& nums) {
+        int result = 0, inc = -1;
+        for (int i = 0; i + 1 < size(nums); ++i) {
+            if (nums[i] < nums[i + 1]) {
+                result += (inc == 0) ? 1 : 0;
+                inc = 1;
+            } else if (nums[i] > nums[i + 1]) {
+                result += (inc == 1) ? 1 : 0;
+                inc = 0;
+            }
+        }
+        return result;
+    }
+};