寒假欢乐赛（循环2）

2的幂整除

#include <bits/stdc++.h>
using namespace std;

int main() {
	int n, cnt = 0;
	cin >> n;
	
	while (n%2 == 0) {
		cnt ++;
		n /= 2;
	}

	cout << cnt;
	
	return 0;
}

分数求和

#include <bits/stdc++.h>
using namespace std;

int main() {
	int n;
	double ans = 0;
	cin >> n;
	
	for (int i = 1; i <= n; i ++) {
		if (i%2 == 1) ans += 1.0 / i;
		else ans -= 1.0 / i;
	}
	
	printf("%.1f", ans);
	
	return 0;
}

打印菱形

#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;

    for (int i = 1; i < n; i++) {
        for (int j = 1; j <= n - i; j++) cout << ' ';
        cout << 'O';
        for (int j = 1; j <= 2 * i - 3; j++) cout << ' ';
        if (i != 1)
            cout << 'O';
        cout << endl;
    }

    for (int i = n; i >= 1; i--) {
        for (int j = 1; j <= n - i; j++) cout << ' ';
        cout << 'O';
        for (int j = 1; j <= 2 * i - 3; j++) cout << ' ';
        if (i != 1)
            cout << 'O';
        cout << endl;
    }

    return 0;
}

cry的大风车

#include <iostream>
#include <cstdio>
using namespace std;

int main() {
	int n;
	cin >> n;
	
	for (int i = 1; i < n; i ++) {
		for (int j = 1; j <= i; j ++) cout << ' ';
		for (int j = n-i; j >= 1; j --) cout << '*';
		for (int j = n-i; j >= 1; j --) cout << ' ';		
		for (int j = 1; j <= i; j ++) cout << '*';
		cout << endl;
	}
	
	for (int i = 1; i <= 2*n; i ++) cout << '*';
	cout << endl;

	for (int i = 1; i < n; i ++) {
		for (int j = n-i; j >= 1; j --) cout << '*';
		for (int j = 1; j <= i; j ++) cout << ' ';
		for (int j = 1; j <= i; j ++) cout << '*';
		//for (int j = n-i; j >= 1; j --) cout << ' ';		
		cout << endl;
	}
	
	return 0;
}

DNA

#include <iostream>
using namespace std;
 
 
int main() {
    int n;
    cin >> n;
     
    while (n --) {
        int a, b;
        cin >> a >> b;
     
        for (int k = 1; k <= b; k ++) {
            for (int i = 1; i < a; i ++) {
                for (int j = 1; j <= a; j ++) {
                    if (i==j || i+j==a+1) cout << 'X';
                    else cout << ' ';
                }
                cout << endl;
            }
        }
        cout << 'X';
        for (int i = 2; i < a; i ++) cout << ' ';
        cout << 'X' << endl;
         
        cout << endl;
    }
 
    return 0;
}