Update 0279.完全平方数.md about Rust

problems/0279.完全平方数.md

@@ -345,6 +345,29 @@ function numSquares(n: number): number {
 };
 ```
 
+Rust:
+
+```rust
+// 先遍历背包
+impl Solution {
+    pub fn num_squares(n: i32) -> i32 {
+        let n = n as usize;
+        let mut dp = vec![i32::MAX; n + 1];
+        dp[0] = 0;
+        for i in 0..=n {
+            let mut j = 1;
+            loop {
+                match j * j > i {
+                    true => break,
+                    false => dp[i] = dp[i].min(dp[i - j * j] + 1),
+                }
+                j += 1;
+            }
+        }
+        dp[n]
+    }
+}
+```
 
 
 <p align="center">