Update 10.3 跳台阶.md

题目链接改为力扣中的对应题目，题目描述和代码按该题的接口调整。

notes/10.3 跳台阶.md

@@ -2,7 +2,7 @@
 
 ## 题目链接
 
-[牛客网](https://www.nowcoder.com/practice/8c82a5b80378478f9484d87d1c5f12a4?tpId=13&tqId=11161&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
+[Leetcode](https://leetcode.cn/problems/qing-wa-tiao-tai-jie-wen-ti-lcof/)
 
 ## 题目描述
 
@@ -25,13 +25,13 @@
 <div align="center"> <img src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/508c6e52-9f93-44ed-b6b9-e69050e14807.jpg" width="350px"> </div><br>
 
 ```java
-public int JumpFloor(int n) {
-    if (n <= 2)
-        return n;
-    int pre2 = 1, pre1 = 2;
+public int trainWays(int num) {
+    if (num <= 1)
+        return 1;
+    int pre2 = 1, pre1 = 1;
     int result = 0;
-    for (int i = 2; i < n; i++) {
-        result = pre2 + pre1;
+    for (int i = 2; i <= num; i++) {
+        result = (pre2 + pre1) % 1000000007;
         pre2 = pre1;
         pre1 = result;
     }