feat: add rust solution to lc problem: No.0521

No.0521.Longest Uncommon Subsequence I

Author: YangFong

Diff for: solution/0500-0599/0521.Longest Uncommon Subsequence I/README.md

@@ -78,6 +78,19 @@ class Solution {
 }
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    pub fn find_lu_slength(a: String, b: String) -> i32 {
+        if a == b {
+            return -1;
+        }
+        a.len().max(b.len()) as i32
+    }
+}
+```
+
 ### **...**
 
 ```

Diff for: solution/0500-0599/0521.Longest Uncommon Subsequence I/README_EN.md

@@ -75,6 +75,19 @@ class Solution {
 }
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    pub fn find_lu_slength(a: String, b: String) -> i32 {
+        if a == b {
+            return -1;
+        }
+        a.len().max(b.len()) as i32
+    }
+}
+```
+
 ### **...**
 
 ```

Diff for: solution/0500-0599/0521.Longest Uncommon Subsequence I/Solution.rs

@@ -0,0 +1,8 @@
+impl Solution {
+    pub fn find_lu_slength(a: String, b: String) -> i32 {
+        if a == b {
+            return -1;
+        }
+        a.len().max(b.len()) as i32
+    }
+}