70. 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?

public class Solution {    public int climbStairs(int n) {        if (n == 0 || n == 1)      return 1;    int pre = 1;    int current = 1;    for (int i = 2; i <= n; i++) {      int temp = current + pre;      pre = current;      current = temp;    }    return current;    }}