愛比的新手筆記

You are climbing a staircase. It takes n steps to reach the top.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Example 1:

Input: n = 2 Output: 2 Explanation: There are two ways to climb to the top. 1. 1 step + 1 step 2. 2 steps

Example 2:

Input: n = 3 Output: 3 Explanation: There are three ways to climb to the top. 1. 1 step + 1 step + 1 step 2. 1 step + 2 steps 3. 2 steps + 1 step

Constraints:

• 1 <= n <= 45

每次扣掉走1階及扣掉走2階後, 要算走幾次就是記下前次和前前次拿來加總即可

public int ClimbStairs(int n)
{
    int pre0 = 1;//前前次有幾種走法
    int pre1 = 1;//前次有幾種走法
    int count = 1;
    for (int i = 2; i <= n; i++)
    {
        count = pre0 + pre1;
        pre0 = pre1;
        pre1 = count;
    }
    return count;
}

Taiwan is a country. 臺灣是我的國家