算法分析与设计课程——LeetCode刷题之 Climbing Stairs

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题目：

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

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

Note: Given n will be a positive integer.

Example 1:

Input: 2
Output:  2
Explanation:  There are two ways to climb to the top.

1. 1 step + 1 step
2. 2 steps

Example 2:

Input: 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

答案：

public int climbStairs(int n) {
        int[] tmp = new int[n];
        if (n < 2){
            return 1;
        }
        tmp[0] = 1;
        tmp[1] = 2;
        for (int i = 2; i < n; i++){
            tmp[i] = tmp[i-1] + tmp[i-2];
        }
        return tmp[n-1];
    }