Create minimum-cost-tree-from-leaf-values.py

Author: kamyu104

Python/minimum-cost-tree-from-leaf-values.py

@@ -0,0 +1,18 @@
+# Time:  O(n)
+# Space: O(n)
+
+class Solution(object):
+    def mctFromLeafValues(self, arr):
+        """
+        :type arr: List[int]
+        :rtype: int
+        """
+        result = 0
+        stk = [float("inf")]
+        for x in arr:
+            while stk[-1] <= x:
+                result += stk.pop() * min(stk[-1], x)
+            stk.append(x)
+        while len(stk) > 2:
+            result += stk.pop() * stk[-1]
+        return result