70. Climbing Stairs

class Solution {public:    int climbStairs(int n) {        int *d=new int [n+1];        d[1]=1;        d[2]=2;        for(int i=3;i<=n;i++)        {            d[i]=d[i-1]+d[i-2];        }        int num=d[n];        delete[] d;         return num;    }};