diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md
index a825b815..1f99a7a5 100644
--- a/problems/0093.复原IP地址.md
+++ b/problems/0093.复原IP地址.md
@@ -566,14 +566,24 @@ function restoreIpAddresses(s: string): string[] {
 
 ```Rust
 impl Solution {
-    fn is_valid(s: &Vec<char>, start: usize, end: usize) -> bool {
-        if start > end { return false; }
-        if s[start] == '0' && start != end { return false; }
+    fn is_valid(s: &[char], start: usize, end: usize) -> bool {
+        if start > end {
+            return false;
+        }
+        if s[start] == '0' && start != end {
+            return false;
+        }
         let mut num = 0;
-        for i in start..=end {
-            if s[i] > '9' || s[i] < '0' { return false; }
-            if let Some(digit) = s[i].to_digit(10) { num = num * 10 + digit; }
-            if num > 255 { return false; }
+        for &c in s.iter().take(end + 1).skip(start) {
+            if !('0'..='9').contains(&c) {
+                return false;
+            }
+            if let Some(digit) = c.to_digit(10) {
+                num = num * 10 + digit;
+            }
+            if num > 255 {
+                return false;
+            }
         }
         true
     }