# Climbing Stairs

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?

Example

Given an example n=3 , 1+1+1=2+1=1+2=3

return 3

```
public class Solution {
/**
* @param n: An integer
* @return: An integer
*/
public int climbStairs(int n) {
if (n <= 1) {
return 1;
}
int[] sum = new int[n + 1];
sum[0] = 0;
sum[1] = 1;
sum[2] = 2;
for (int i = 3; i <= n; i++) {
sum[i] = sum[i - 1] + sum[i - 2];
}
return sum[n];
}
}
```

Hope this helps,

Michael