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

Author: kamyu104

C++/minimum-cost-tree-from-leaf-values.cpp

@@ -0,0 +1,22 @@
+// Time:  O(n)
+// Space: O(n)
+
+class Solution {
+public:
+    int mctFromLeafValues(vector<int>& arr) {
+        int result = 0;
+        vector<int> stk = {numeric_limits<int>::max()};
+        for (const auto& x : arr) {
+            while (stk.back() <= x) {
+                const auto mid = move(stk.back()); stk.pop_back();
+                result += mid * min(stk.back(), x);
+            }
+            stk.emplace_back(x);
+        }
+        while (stk.size() > 2) {
+            const auto right = move(stk.back()); stk.pop_back();
+            result += right * stk.back();
+        }
+        return result;
+    }
+};