feat: add rust solution to lc problem: No.65 (doocs#2114)

Author: herschel-ma

solution/0000-0099/0065.Valid Number/README.md

@@ -260,6 +260,71 @@ public class Solution {
 }
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    pub fn is_number(s: String) -> bool {
+        let mut i = 0;
+        let n = s.len();
+
+        if let Some(c) = s.chars().nth(i) {
+            if c == '+' || c == '-' {
+                i += 1;
+                if i == n {
+                    return false;
+                }
+            }
+        }
+        if let Some(x) = s.chars().nth(i) {
+            if x == '.'
+                && (i + 1 == n
+                    || if let Some(m) = s.chars().nth(i + 1) {
+                        m == 'e' || m == 'E'
+                    } else {
+                        false
+                    })
+            {
+                return false;
+            }
+        }
+
+        let mut dot = 0;
+        let mut e = 0;
+        let mut j = i;
+
+        while j < n {
+            if let Some(c) = s.chars().nth(j) {
+                if c == '.' {
+                    if e > 0 || dot > 0 {
+                        return false;
+                    }
+                    dot += 1;
+                } else if c == 'e' || c == 'E' {
+                    if e > 0 || j == i || j == n - 1 {
+                        return false;
+                    }
+                    e += 1;
+                    if let Some(x) = s.chars().nth(j + 1) {
+                        if x == '+' || x == '-' {
+                            j += 1;
+                            if j == n - 1 {
+                                return false;
+                            }
+                        }
+                    }
+                } else if !c.is_ascii_digit() {
+                    return false;
+                }
+            }
+            j += 1;
+        }
+
+        true
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0000-0099/0065.Valid Number/README_EN.md

@@ -248,6 +248,68 @@ public class Solution {
 }
 ```
 
+### **Rust**
+
+```rust
+impl Solution {
+    pub fn is_number(s: String) -> bool {
+        let mut i = 0;
+        let n = s.len();
+
+        if let Some(c) = s.chars().nth(i) {
+            if c == '+' || c == '-' {
+                i += 1;
+                if i == n {
+                    return false;
+                }
+            }
+        }
+        if let Some(x) = s.chars().nth(i) {
+            if
+                x == '.' &&
+                (i + 1 == n ||
+                    (if let Some(m) = s.chars().nth(i + 1) { m == 'e' || m == 'E' } else { false }))
+            {
+                return false;
+            }
+        }
+
+        let mut dot = 0;
+        let mut e = 0;
+        let mut j = i;
+
+        while j < n {
+            if let Some(c) = s.chars().nth(j) {
+                if c == '.' {
+                    if e > 0 || dot > 0 {
+                        return false;
+                    }
+                    dot += 1;
+                } else if c == 'e' || c == 'E' {
+                    if e > 0 || j == i || j == n - 1 {
+                        return false;
+                    }
+                    e += 1;
+                    if let Some(x) = s.chars().nth(j + 1) {
+                        if x == '+' || x == '-' {
+                            j += 1;
+                            if j == n - 1 {
+                                return false;
+                            }
+                        }
+                    }
+                } else if !c.is_ascii_digit() {
+                    return false;
+                }
+            }
+            j += 1;
+        }
+
+        true
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0000-0099/0065.Valid Number/Solution.rs

@@ -0,0 +1,57 @@
+impl Solution {
+    pub fn is_number(s: String) -> bool {
+        let mut i = 0;
+        let n = s.len();
+
+        if let Some(c) = s.chars().nth(i) {
+            if c == '+' || c == '-' {
+                i += 1;
+                if i == n {
+                    return false;
+                }
+            }
+        }
+        if let Some(x) = s.chars().nth(i) {
+            if
+                x == '.' &&
+                (i + 1 == n ||
+                    (if let Some(m) = s.chars().nth(i + 1) { m == 'e' || m == 'E' } else { false }))
+            {
+                return false;
+            }
+        }
+
+        let mut dot = 0;
+        let mut e = 0;
+        let mut j = i;
+
+        while j < n {
+            if let Some(c) = s.chars().nth(j) {
+                if c == '.' {
+                    if e > 0 || dot > 0 {
+                        return false;
+                    }
+                    dot += 1;
+                } else if c == 'e' || c == 'E' {
+                    if e > 0 || j == i || j == n - 1 {
+                        return false;
+                    }
+                    e += 1;
+                    if let Some(x) = s.chars().nth(j + 1) {
+                        if x == '+' || x == '-' {
+                            j += 1;
+                            if j == n - 1 {
+                                return false;
+                            }
+                        }
+                    }
+                } else if !c.is_ascii_digit() {
+                    return false;
+                }
+            }
+            j += 1;
+        }
+
+        true
+    }
+}