Merge pull request neetcode-gh#1290 from zim0369/268

Create 268-Missing-Number.rs

Author: Ahmad-A0

rust/268-Missing-Number.rs

@@ -0,0 +1,10 @@
+impl Solution {
+    pub fn missing_number(nums: Vec<i32>) -> i32 {
+        let length = nums.len() as i32;
+        let mut ans = length;
+        for i in 0..length {
+            ans ^= i ^ nums[i as usize];
+        }
+        ans
+    }
+}