题解 | 牛牛学数列6
牛牛学数列6
https://www.nowcoder.com/practice/b6321648517247b2ac2e2f80cbc63ae1
#include <iostream>
using namespace std;
int main() {
int a, b,c;
int num;
while (cin >> num) { // 使用迭代法
if (num < 1 || num > 20) break;
//已经前三项，abc分别表示前三项,curr表示当前项
a = 0;
b = 1;
c = 1;
int curr;
for (int i = 4; i <= num; ++i) {
curr = a + 2 * b + c;
//更新迭代
a = b;
b = c;
c = curr;
}
cout << curr << endl;
}
}
