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?

class  Solution {
public:
     int climbStairs( int n) {
         int step[n];
        step[ 0]= 1;
        step[ 1]= 1;
         for( int i= 2;i<=n;i++)
            step[i]=step[i- 1]+step[i- 2];
         return step[n];
    }
};