ACM练习题——爬楼梯

Climbing_Stairs
Description

You are climbing a stair case. It takes n steps to reach to the top.
你在爬楼梯。它需要n步才能到达顶点。

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

每次你可以爬1级或2级。有多少种不同的方法可以爬到顶端?

Input

NONE

Output

NONE

Sample Input 1

2
Sample Output 1

2
Sample Input 2

3
Sample Output 2

3
Hint

For EX1:

1. 1 step + 1 step

2. 2 steps

For EX2:

1. 1 step + 1 step + 1 step

2. 1 step + 2 steps

3. 2 steps + 1 step

PS:1 <= n <= 45

其实这道题挺简单的，看一下你就懂了
思路：
从第三项开始，每一项都是前两项之和。

#include<stdio.h>
int main(void){
	int n,i,num;
	int a[200];
	a[0]=1;
	a[1]=2;
	for(i=2;i<200;i++){
		a[i]=a[i-2]+a[i-1];
	}
	while(scanf("%d",&n) != EOF){
		printf("%d\n",a[n-1]);
	}
	return 0;
}```