Update 0322.零钱兑换.md about rust

problems/0322.零钱兑换.md

@@ -315,18 +315,24 @@ func min(a, b int) int {
 Rust:
 
 ```rust
-pub fn coin_change(coins: Vec<i32>, amount: i32) -> i32 {
-    let amount = amount as usize;
-    let mut dp = vec![i32::MAX; amount + 1];
-    dp[0] = 0;
-    for i in 0..coins.len() {
-        for j in coins[i] as usize..=amount {
-            if dp[j - coins[i] as usize] != i32::MAX {
-                dp[j] = dp[j].min(dp[j - coins[i] as usize] + 1);
+// 遍历物品
+impl Solution {
+    pub fn coin_change(coins: Vec<i32>, amount: i32) -> i32 {
+        let amount = amount as usize;
+        let mut dp = vec![i32::MAX; amount + 1];
+        dp[0] = 0;
+        for coin in coins {
+            for i in coin as usize..=amount {
+                if dp[i - coin as usize] != i32::MAX {
+                    dp[i] = dp[i].min(dp[i - coin as usize] + 1);
+                }
             }
         }
+        if dp[amount] == i32::MAX {
+            return -1;
+        }
+        dp[amount]
     }
-    if dp[amount] == i32::MAX { -1 } else { dp[amount] }
 }
 ```