小白也看得懂的题解

#include <bits/stdc++.h>
using namespace std;
int a[45] , n , sum;
int main(){
    cin >> n;
    a[1] = 1 , a[2] = 1;
    for(int i = 3 ; i <= n ; i++){
        a[i] = a[i - 2] + a[i - 1];
    }
    cout << a[n];
	return 0;
}