牛客竞赛语法入门班选择结构习题C++版本参考代码及部分解析

牛客竞赛语法入门班选择结构习题

C语言版本的参考代码

重点题：
F 吃瓜群众
H 小名的回答
N 送分题
O 四季
P B是不是太迟了

A 比大小

#include <iostream>
using namespace std;
int main()
{
    int a,b;
    cin >> a >> b;
    if (a > b) cout << ">";
    else if (a == b) cout << "=";
    else cout << "<";
    return 0;
}

B 卡拉兹函数

#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    if (n % 2) cout << 3 * n + 1;
    else cout << n / 2;
    return 0;
}

C 默契

#include <iostream>
using namespace std;
int main()
{
    int a,b;
    cin >> a >> b;
    if (a == b) cout << "Tacit！";
    else cout << "No Tacit!";
    return 0;
}

D 整除判断

#include <iostream>
using namespace std;
int main()
{
    int a,b;
    cin >> a >> b;
    if (a % b) cout << "NO";
    else cout << "YES";
    return 0;
}

E CSimplemathproblem

需要开long long

#include <iostream>
using namespace std;
int main()
{
    long long a,b;
    cin >> a >> b;
    if (b % a) cout << b - a;
    else cout << b + a;
    return 0;
}

F 吃瓜群众

两个偶数之和一定是偶数，即如果这个数字是偶数，就可以分解为两个偶数的部分；

需要对数字2进行特判

#include <iostream>
using namespace std;
int main()
{
    int a;
    cin >> a;
    if (a % 2 || a == 2) cout << "NO, you can't divide the watermelon into two even parts.";
    else cout << "YES, you can divide the watermelon into two even parts.";
    return 0;
}

G jyq跳格子

从1开始，每次加2或者加4，多次之后最后的结果一定是奇数。故若输入是奇数则输出其本身，若输出数据是偶数则输出-1

#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    if (n % 2) cout << n;
    else cout << "-1";
    return 0;
}

H 小名的回答

I 牛妹数

#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    if (! (n % 2) && n > 50) cout << "yes";
    else cout << "no";
    return 0;
}

J 判断闰年

闰年的判断方法：
① 是4的倍数，且不是100的倍数；
② 是400的倍数。
满足其中之一的年份是闰年

#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    if (n % 4 == 0 && n % 100 || n % 400 == 0) cout << "yes";
    else cout << "no";
    return 0;
}

K 统计数据正负个数

#include <iostream>
using namespace std;
int main()
{
	long long n;
	int po = 0,ne = 0;//赋初始值
	while (cin >> n)
		if (n > 0) po++;
		else if (n < 0) ne++;
	cout << "positive:" << po << endl << "negative:" << ne;
	return 0;
}

L 小乐乐是否被叫家长

#include <iostream>
using namespace std;
int main()
{
    int a,b,c;
    cin >> a >> b >> c;
    double ans = 1.0 * (a + b + c) / 3;
    if (ans >= 60) cout << "NO";
    else cout << "YES";
    return 0;
}

M 最大最小值

0x3f3f3f3f是10 ^ 9级别大小

#include <iostream>
using namespace std;
int main()
{
    int a,b,c;
    int maxn = 0,minn = 0x3f3f3f3f;
    cin >> a >> b >> c;
    if (maxn < a) maxn = a;
    if (maxn < b) maxn = b;
    if (maxn < c) maxn = c;
    if (minn > a) minn = a;
    if (minn > b) minn = b;
    if (minn > c) minn = c;
    cout << "The maximum number is : " << maxn << endl;
    cout << "The minimum number is : " << minn << endl;
    return 0;
}

N 送分题

O 四季

#include <iostream>
using namespace std;
int main()
{
    int year,month;
    scanf("%4d%2d",&year,&month);//取出月份的方法
    if (month >= 3 && month <= 5) cout << "spring";
    else if (month >= 6 && month <= 8) cout << "summer";
    else if (month >= 9 && month <= 11) cout << "autumn";
    else cout << "winter";
    return 0;
}

P B是不是太迟了

错误代码：测试样例为2020/09/30回输出QAQ

#include <iostream>
using namespace std;
int main()
{
    int a,b,c;
    scanf("%d/%d/%d",&a,&b,&c);
    if (b <= 10 && c < 29) printf("No. It's not too late.");
    else printf("QAQ");
    return 0;
}

AC代码：

#include <iostream>
using namespace std;
int main()
{
    int a,b,c;
    scanf("%d/%d/%d",&a,&b,&c);
    if (b < 10) printf("No. It's not too late.");
    else if (b == 10 && c < 29) printf("No. It's not too late.");
    else printf("QAQ");
    return 0;
}