diff --git a/problems/0746.使用最小花费爬楼梯.md b/problems/0746.使用最小花费爬楼梯.md
index 98a58c12..3d014858 100644
--- a/problems/0746.使用最小花费爬楼梯.md
+++ b/problems/0746.使用最小花费爬楼梯.md
@@ -330,22 +330,27 @@ var minCostClimbingStairs = function(cost) {
 
 ```typescript
 function minCostClimbingStairs(cost: number[]): number {
-    /**
-        dp[i]: 走到第i阶需要花费的最少金钱
-        dp[0]: 0;
-        dp[1]: 0;
-        ...
-        dp[i]: min(dp[i - 1] + cost[i - 1], dp[i - 2] + cost[i - 2]);
-     */
-    const dp = [];
-    const length = cost.length;
-    dp[0] = 0;
-    dp[1] = 0;
-    for (let i = 2; i <= length; i++) {
-        dp[i] = Math.min(dp[i - 1] + cost[i - 1], dp[i - 2] + cost[i - 2]);
-    }
-    return dp[length];
-};
+  const dp = [0, 0]
+  for (let i = 2; i <= cost.length; i++) {
+    dp[i] = Math.min(dp[i - 1] + cost[i - 1], dp[i - 2] + cost[i - 2])
+  }
+  return dp[cost.length]
+}
+```
+
+不使用 dp 数组
+
+```typescript
+function minCostClimbingStairs(cost: number[]): number {
+  let dp_before = 0,
+    dp_after = 0
+  for (let i = 2; i <= cost.length; i++) {
+    let dpi = Math.min(dp_before + cost[i - 2], dp_after + cost[i - 1])
+    dp_before = dp_after
+    dp_after = dpi
+  }
+  return dp_after
+}
 ```
 
 ### Rust