Update 0746.使用最小花费爬楼梯.md

problems/0746.使用最小花费爬楼梯.md

@@ -312,17 +312,30 @@ func min(a, b int) int {
 ```
 
 
-### Javascript 
+### JavaScript 
+
 ```Javascript
 var minCostClimbingStairs = function(cost) {
-    const n = cost.length;
-    const dp = new Array(n + 1);
-    dp[0] = dp[1] = 0;
-    for (let i = 2; i <= n; ++i) {
-        dp[i] = Math.min(dp[i -1] + cost[i - 1], dp[i - 2] + cost[i - 2])
+  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
+
+```JavaScript
+var minCostClimbingStairs = function(cost) {
+  let dpBefore = 0,
+    dpAfter = 0
+    for(let i = 2;i <= cost.length;i++){
+        let dpi = Math.min(dpBefore + cost[i - 2],dpAfter + cost[i - 1])
+        dpBefore = dpAfter
+        dpAfter = dpi
     }
-    
-    return dp[n]
+    return dpAfter
 };
 ```
 
@@ -342,14 +355,14 @@ function minCostClimbingStairs(cost: number[]): number {
 
 ```typescript
 function minCostClimbingStairs(cost: number[]): number {
-  let dp_before = 0,
-    dp_after = 0
+  let dpBefore = 0,
+    dpAfter = 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
+    let dpi = Math.min(dpBefore + cost[i - 2], dpAfter + cost[i - 1])
+    dpBefore = dpAfter
+    dpAfter = dpi
   }
-  return dp_after
+  return dpAfter
 }
 ```