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#include <bits/stdc++.h>
using namespace std;
// 递归
// 分析:用树图进行分析,说明分枝多,重复多,计算多,速度慢,容易爆栈.从未知到已知,自我调用
int louti(int n) {
if (n == 1) return 1;
if (n == 2) return 2;
return louti(n - 1) + louti(n - 2);
}
//递推
// 分析:无多余运算,速度快,性能好,从已知至未知,推导
int louti2(int n) {
int a = 1, b = 2, c = 0, i = 3;
if (n == 1) return a;
if (n == 2) return b;
while (i <= n) {
c = a + b;
a = b;
b = c;
i++;
}
return c;
}
int main() {
int n;
cin >> n;
//递归
cout << louti(n) << endl;
//递推
cout << louti2(n) << endl;
return 0;
}