diff --git a/AcWing/68/68.cpp b/AcWing/68/68.cpp
new file mode 100644
index 00000000..4cee14c4
--- /dev/null
+++ b/AcWing/68/68.cpp
@@ -0,0 +1,13 @@
+class Solution {
+  public:
+    int getMissingNumber(vector<int>& nums) {
+        set<int> s;
+        for (int i = 0; i <= nums.size(); i++) {
+            s.insert(i);
+        }
+        for (int i : nums) {
+            s.erase(i);
+        }
+        return *s.begin();
+    }
+};