作业3

实验1

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <windows.h>
#define N 80
void print_text(int line, int col, char text[]);
void print_spaces(int n);
void print_blank_lines(int n);
int main() {
    int line, col, i;
    char text[N] = "hi, November~";
    srand(time(0));
    for (i = 1; i <= 10; ++i) {
        line = rand() % 25;
        col = rand() % 80;
        print_text(line, col, text);
        Sleep(1000);
    }
    return 0;
}
void print_spaces(int n) {
    int i;
    for (i = 1; i <= n; ++i)
        printf(" ");
}
void print_blank_lines(int n) {
    int i;
    for (i = 1; i <= n; ++i)
        printf("\n");
}
void print_text(int line, int col, char text[]) {
    print_blank_lines(line - 1);
    print_spaces(col - 1);
    printf("%s", text);
}

　　实验2

task 2.1

#include <stdio.h>
#include <stdlib.h>
long long fac(int n);
int main()
{
    int i, n;
    printf("Enter n: ");
    scanf("%d", &n);
    for (i = 1; i <= n; ++i)
        printf("%d! = %lld\n", i, fac(i));
    system("pause");
    return 0;
}
long long fac(int n) {
    static long long p = 1;
    printf("p = %lld\n", p);
    p = p * n;
    return p;
}

　　

 

 此处static是用来保存上一次程序运行的结果。

task 2.2

#include <stdio.h>
#include <stdlib.h>
int func(int, int);
int main() {
	int k = 4, m = 1, p1, p2;
	p1 = func(k, m);
	p2 = func(k, m);
	printf("%d, %d\n", p1, p2);
	system("pause");
	return 0;
}
int func(int a, int b) {
	static int m = 0, i = 2;
	i += m + 1;
	m = i + a + b;
	return m;
}

　　实验3

#include <stdio.h>
long long func(int n);
int main() {
    int n;
    long long f;
    while (scanf("%d", &n) != EOF) {
        f = func(n);
        printf("n = %d, f = %lld\n", n, f);
    }
    return 0;
}
long long fun(int n);
long long func(int n)
{
    return fun(n) - 1;

}
long long fun(int n)
{
    if (n == 0)
        return 1;
    return 2 * fun(n - 1);
}

　　

 

 实验4

#include <stdio.h>
int func(int n, int m);
int main() {
    int n, m;
    while (scanf("%d%d", &n, &m) != EOF)
        printf("n = %d, m = %d, ans = %d\n", n, m, func(n, m));
    return 0;
}
int func(int n, int m)
{
    if (m == n)
        return 1;
    else if (m == 0)
        return 1;
    else if (n < 0)
        return 0;
    else
        return func(n - 1, m) + func(n - 1, m - 1);
}

　　

 

 实验5

#include <stdio.h>
int mul(int n, int m);
int main()
{
	int n, m;
	while (scanf("%d%d", &n, &m) != EOF)
		printf("%d * %d = %d\n", n, m, mul(n, m));
	return 0;
} int mul(int n, int m)
{
	if (n == 0)
		return 0;
	return m + mul(n - 1, m);
}

　　

 

 实验6

#include <stdio.h>
#include <stdlib.h>
int m = 0;
void move(int n, char a, char c)
{
printf("%d:%c-->%c\n", n, a, c);
m++;
}
void hanoi(int n, char a, char b, char c)
{
if (n == 1)
move(n, a, c);
else
{
hanoi(n - 1, a, c, b);
move(n, a, c);
hanoi(n - 1, b, a, c);
}
}
int main()
{
int n;
char a = 'A', b = 'B', c = 'C';
while (scanf_s("%d", &n) != EOF)
{
hanoi(n, a, b, c);
printf("共移动了%d次\n", m);
}
system("pause");
return 0;
}

　　

 

 实验7

#include <stdio.h>
#include <stdlib.h>
int is_prime(int);
int main()
{
    int sum, a, b;
    for (sum = 2;sum <= 20;sum = sum + 2)
    {
        for (a = 1;a <= 17;a++)
        {
            if (is_prime(a))
            {
                for (b = 1;b <= 17;b++)
                {
                    if (is_prime(b) && a <= b)
                    {
                        if (sum == a + b)
                        {
                            printf("%d =%d + %d", sum, a, b);
                            printf("\n");
                        }

                    }
                }
            }
        }
    }
    system("pause");
}
int is_prime(int n)
{
    int i;
    if (n <= 1)
        return 0;
    for (i = 2; i < n; i++)
        if (n % i == 0)
            return 0;
    return 1;
}

　　

 

 实验8

#include <stdio.h>
long fun(long s);
int main() {
    long s, t;
    printf("Enter a number: ");
    while (scanf("%ld", &s) != EOF) {
        t = fun(s);
        printf("new number is: %ld\n\n", t);
        printf("Enter a number: ");
    }
    return 0;
}
long fun(long s)
{
    int x[100];
    long a;
    int i = 0, b;
    for (;s != 0;s = s / 10)
    {
        a = s % 10;
        if (a % 2 != 0)
        {
            x[i] = a;
            i++;
        }
    }

    for (b = i - 1;b >= 0;b--)
        s = s * 10 + x[b];
    return s;
}