Create validate-stack-sequences.cpp

Author: kamyu104

C++/validate-stack-sequences.cpp

@@ -0,0 +1,20 @@
+// Time:  O(n)
+// Space: O(n)
+
+class Solution {
+public:
+    bool validateStackSequences(vector<int>& pushed, vector<int>& popped) {
+        int i = 0;
+        vector<int> s;
+        for (const auto& v : pushed) {
+            s.emplace_back(v);
+            while (!s.empty() &&
+                   i < popped.size() &&
+                   s.back() == popped[i]) {
+                s.pop_back();
+                ++i;
+            }
+        }
+        return i == popped.size();
+    }
+};