diff --git a/problems/0122.买卖股票的最佳时机II（动态规划）.md b/problems/0122.买卖股票的最佳时机II（动态规划）.md
index 5976f258..43e567c5 100644
--- a/problems/0122.买卖股票的最佳时机II（动态规划）.md
+++ b/problems/0122.买卖股票的最佳时机II（动态规划）.md
@@ -384,9 +384,10 @@ impl Solution {
 impl Solution {
     pub fn max_profit(prices: Vec<i32>) -> i32 {
         let mut dp = vec![-prices[0], 0];
-        for i in 1..=prices.len() {
-            dp[0] = dp[0].max(dp[1] - prices[i - 1]);
-            dp[1] = dp[1].max(dp[0] + prices[i - 1]);
+        for p in prices {
+            // 可以看作 low、res
+            dp[0] = dp[0].max(dp[1] - p);
+            dp[1] = dp[1].max(dp[0] + p);
         }
         dp[1]
     }