C++編程題集（二）

1.

int main()
{  
    char ch[4];
    cin >> ch;
	int a, b, c, d;
	a = ch[0] - '0';
	b = ch[1] - '0';
	c = ch[2] - '0';
	d = ch[3] - '0';
	a = (a + 8) % 7;
	b = (b + 8) % 7;
	c = (c + 8) % 7;
	d = (d + 8) % 7;
	int m, n;
	m = a;
	a = b;
	b = m;
	n = c;
	c = d;
	d = n;
	ch[0] = '0' + a;
	ch[1] = '0' + b;
	ch[2] = '0' + c;
	ch[3] = '0' + d;
	cout << ch;
	//write your own codes
	return 0;
}

2.

3.a+aa+aaa+…（n個a）之和

int main()
{
    int a,n;
    cin>>a>>n;
    int sum=0,item=0;
    for(int i=0;i<n;i++)
    {
        item=item*10+a;
        sum+=item;
    }
    cout<<sum;
    //write your own codes
    return 0;
}

4.

int main()
{ 
    int n;
    cin>>n;
    int i,j,k,cnt;
     cnt=0;

for(i=1;i<n+1;i++)

for(j=0;j<n+1;j++)

if(i==j)continue;

else for(k=0;k<n+1;k++)

if( k!=i&&k!=j) cnt++;
cout<<cnt;
//write your own code  
    return 0;
}

5.

int main()
{ 
    int n;
    cin>>n;
    int i,j,k,cnt;
     cnt=0;

for(i=1;i<n+1;i++)

for(j=0;j<n+1;j++)

if(i==j)continue;

else for(k=0;k<n+1;k+=2)

if( k!=i&&k!=j) cnt++;
cout<<cnt;
//write your own code  
    return 0;
}

6.

int main()
{
    int n;
    int arr[25]; // 聲明數組  
    arr[0] = arr[1] = 1;
    for(int i = 2; i < 25; i++) // 把前20項的數求出放到數組中
        arr[i] = arr[i - 2] + arr[i - 1];
    while(cin >> n) {
        int sum = 0;
        for(int j = 0; j < n; j++) // 求前n項的和
        { 
            sum += arr[j];
        }
        cout<< sum << endl;
    }
	//write your code here
	return 0;
}

7.

int main() 
{  
    int n;
    cin>>n;
    double sum=0;
    int item=1,a=0;
    for(int i=1;i<=n;i++)
    {
        item*=i;
        a=2*i-1;
        sum+=(double)a/item;
    }
    cout<<sum;
    //write your own codes 
    return 0;
}

8.

#include <iostream>
using namespace std;
int gcd(int a,int b)
{
    while(b)
    {
        int t=a%b;
        a=b;
        b=t;
    }
    return a;
}
int gbs(int a,int b)
{
    return a/gcd(a,b)*b;
}
int main()
{
    int a,b,c;
    cin>>a>>b>>c;
    int min;
    min=gbs(a,b);
    min=gbs(min,c);
    cout<<min;
    //write your code here
    return 0;
}

9.

#include <iostream>
using namespace std;
法一：函數調用
int fun(int n)
{
int m=1,i;
for(i=1;i<=n;i++)
m=m*i;
return m;
}
 
int main()
{
int n,s=0,i;
cin>>n;
for(i=1;i<=2*n-1;i=i+2)
s=s+fun(i);
cout<<s;
return 0;
}
法二：
int main()
{
    int n;
	cin >> n;
	int a=1;
	int sum = 0;
	for (int i = 1; i <= 2 * n - 1; i += 2)
	{
		for (int j = 1; j <= i; j++)
		{
			a *= j;
		}
		sum += a;
		a = 1;
	}
	cout << sum;
	//write your own codes
	return 0;
}

10.

int main()
{
    int i,j;
    int a[4][4];
    int sum=0;
    for( i=0;i<4;i++)
    {
        for(j=0;j<4;j++)
        {
            cin>>a[i][j];
        }
    }
    for(i=0;i<4;i++)
    for(j=i;j<=i;j++)
    sum+=a[i][j];
    for(i=0,j=3;i<4,j>=0;i++,j--)
    sum+=a[i][j];
   cout<<sum;
	//write your code here
    return 0;
}

11.

int main( )
{
  char str[20];
  //從鍵盤輸入字符串保存到字符數組中
  gets(str);
  int n=strlen(str);
  char temp;
  for(int i=0;i<n/2;i++)
  {
      temp=str[i];
      str[i]=str[n-1-i];
      str[n-1-i]=temp;
  }
  //write your own codes
  //輸出逆序後的字符串
  cout<<str;
  return 0;
}