feat: 0070.爬楼梯.md 增加 rust代码

problems/0070.爬楼梯.md

@@ -303,7 +303,7 @@ var climbStairs = function(n) {
 };
 ```
 
-TypeScript
+### TypeScript
 
 > 爬2阶
 
@@ -447,7 +447,26 @@ public class Solution {
 }
 ```
 
+### Rust
 
+```rust
+impl Solution {
+    pub fn climb_stairs(n: i32) -> i32 {
+        if n <= 2 {
+            return n;
+        }
+        let mut a = 1;
+        let mut b = 2;
+        let mut f = 0;
+        for i in 2..n {
+            f = a + b;
+            a = b;
+            b = f;
+        }
+        return f;
+    }
+}
+```
 
 <p align="center">
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">