Add solution 896

Author: vulgur

896_MonotonicArray.swift

@@ -0,0 +1,19 @@
+class Solution {
+    func isMonotonic(_ A: [Int]) -> Bool {
+        if A.count <= 1 {
+            return true
+        }
+
+        let increased = A[A.count-1] >= A[0]
+        for i in 1..<A.count {
+            if A[i] == A[i-1] {
+                continue
+            }
+            let isIncreasing = A[i] >= A[i-1]
+            if isIncreasing != increased {
+                return false
+            }
+        }
+        return true
+    }
+}