Update 0377.组合总和Ⅳ.md 优化 rust

problems/0377.组合总和Ⅳ.md

@@ -253,16 +253,17 @@ Rust
 ```Rust
 impl Solution {
     pub fn combination_sum4(nums: Vec<i32>, target: i32) -> i32 {
-        let mut dp = vec![0; target as usize + 1];
+        let target = target as usize;
+        let mut dp = vec![0; target + 1];
         dp[0] = 1;
-        for i in 1..=target as usize {
-            for &j in nums.iter() {
-                if i as i32 >= j {
-                    dp[i] += dp[i- j as usize];
+        for i in 1..=target {
+            for &n in &nums {
+                if i >= n as usize {
+                    dp[i] += dp[i - n as usize];
                 }
             }
         }
-        return dp[target as usize];
+        dp[target]
     }
 }
 ```