C++ 实现台阶问题：计算小瓜上台阶的方案数

#include "iostream"\nusing namespace std;\n\nint countWays(int n) {\n if (n == 1) {\n return 1;\n }\n if (n == 2) {\n return 2;\n }\n int a = 1, b = 2, c;\n for (int i = 3; i <= n; i++) {\n c = a + b;\n a = b;\n b = c;\n }\n return c;\n}\n\nint main() {\n int n;\n cin >> n;\n int ways = countWays(n);\n cout << ways << endl;\n return 0;\n}