跳台阶问题

#include <iostream>
using namespace std;

int stepJump(int n){
if(n == 1) return 1;
if(n == 2) return 2;
int t1 = 1;
int t2 = 2;
for(int i=3;i<=n;i++) {
int temp = t2;
t2 += t1 ;
t1 = temp;
}
return t2;
}
int main()
{
int n = 100;
cout<<stepJump(20)<<endl;
return 0;

}