蓝桥杯 入门训练

题目链接：http://lx.lanqiao.cn/problemset.page?code=BEGIN

BEGIN-1 A+B问题

#include <bits/stdc++.h>
using namespace std;
int main() {
    int a, b;
    cin >> a >> b;
    cout << a + b << "
";
    return 0;
}

BEGIN-2 序列求和

#include <bits/stdc++.h>
using namespace std;
int main() {
    long long n;
    cin >> n;
    cout << n * (n + 1) / 2 << "
";
    return 0;
}

BEGIN-3 圆的面积

#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1);
int main() {
    int r;
    cin >> r;
    printf("%.7f", PI * r * r);
    return 0;
}

BEGIN-4 Fibonacci数列

#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 100;
const int MOD = 10007;
int main() {
    vector<int> f(N);
    f[1] = f[2] = 1;
    for (int i = 3; i < N; i++) {
        f[i] = (f[i - 1] + f[i - 2]) % MOD;
    }
    int n;
    cin >> n;
    cout << f[n] << "
";
    return 0;
}