problems: add pascals triangle ii

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/pascals-triangle-ii.cpp

@@ -0,0 +1,16 @@
+class Solution {
+public:
+    vector<int> getRow(int rowIndex)
+    {
+        vector<int> result;
+
+        result.push_back(1);
+        for (auto k = 0; k < rowIndex; k++) {
+            auto next = static_cast<int>(
+                static_cast<long>(result.back()) * (rowIndex - k) / (k + 1));
+            result.push_back(next);
+        }
+
+        return result;
+    }
+};