实验三

实验任务1

源码

#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, April~";
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); 
}

实验任务2_1

源码

#include <stdio.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));
	   
	return 0;
}

long long fac(int n){
	static long long p = 1;
	
	p = p * n;
	printf("p = %lld\n", p);
	return p;
}

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实验任务2_2

源码

#include <stdio.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);
	
	return 0;
}


int func(int a, int b)
{
	static int m = 0,i = 2;
	
	i += m + 1;
	m = i+ a + b;
	
	return m;
}

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static变量只能被所在的源文件使用

实验任务3

源码

#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 func(int n) {
    long long s;

    if (n == 1)
        s = 1;
    else
        s = 2 * func(n - 1) + 1;

    return s;

}

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 实验4

源码

#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 (n == m || m == 0) {

		return 1;
	}
	else if (n < m) {
		return 0;
	}

	return func(n - 1, m) + func(n - 1, m - 1);

}

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 实验5-1

源码

#include <stdio.h>
double mypow(int x, int y);
int main()
{
    int x, y;
    double ans;
    while (scanf("%d%d", &x, &y) != EOF)
    {
        ans = mypow(x, y);
        printf("%d的%d次方: %g\n\n", x, y, ans);
    }
    return 0;
}

double mypow(int x, int y)
{
    int i;
    double ans = 1.0;
    if (y >= 0)
    {
        for (i = 1;i <= y;i++)
            ans = ans * x;
        return ans;
    }
    else
    {
        for (i = 1;(i + y) <= 0;i++)
            ans = ans / x;
        return ans;
    }
}

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 5-2

源码

#include <stdio.h>

double mypow(int x, int y);

int main() {

    int x, y;
    double ans;

    while (scanf("%d %d", &x, &y) != EOF) {
        ans = mypow(x, y);
        printf("%d的%d次方：%g\n\n", x, y, ans);
    }

    return 0;
}

double mypow(int x, int y) {
    if (y == 0)
        return 1;
    if (y > 0)
        return x * mypow(x, y - 1);
    if (y < 0)
        return 1.0 / x * mypow(x, y + 1);
}

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 实验6

源码

#include <stdio.h>
#include <stdlib.h>

void hanoi(unsigned int n, char from, char temp, char to);
void moveplate(unsigned int n, char from, char to);

int t;

int main() {
    unsigned int n;

    while (scanf("%u", &n) != EOF) {
        t = 0;

        hanoi(n, 'A', 'B', 'C');

        printf("一共移动了%d次\n", t);
    }

    system("pause");

    return 0;
}

void hanoi(unsigned int n, char from, char temp, char to) {
    if (n == 1)
        moveplate(n, from, to);
    else {
        hanoi(n - 1, from, to, temp);
        moveplate(n, from, to);
        hanoi(n - 1, temp, from, to);
    }
}

void moveplate(unsigned int n, char from, char to) {
    t = t + 1;
    printf("%u: %c --> %c\n", n, from, to);
}

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 实验7

源码

#include<stdio.h>
int is_prime(int n);
int main()
{
    int n, i;
    for (n = 4;n <= 20;n += 2)
    {
        for (i = 2;i <= (n / 2);i++)
        {
            if (is_prime(i) && is_prime(n - i))
            {
                printf("%d = %d + %d\n", n, i, n - i);
                break;
            }
        }
    }
    return 0;
}
int is_prime(int n)
{
    int i, flag = 1;
    for (i = 2;i < n;i++)
    {
        if (n % i == 0)
            flag = 0;
    }
    return flag;
}

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 实验8

源码

#include <stdio.h>
#include <math.h>
long func(long s);

int main()
{
	long s, t;

	printf("Enter a number:");
	while (scanf("%ld", &s) != EOF)
	{
		t = func(s);
		printf("new number is: %ld\n\n", t);
		printf("Enter a number: ");
	}

	return 0;
}

long func(long s)
{
    long ans = 0;
    long x, i = 1;
    while (s != 0)
    {
        x = s % 10, s = s / 10;
        if (x % 2 != 0)
        {
            ans = ans + x * i;
            i = i * 10;
        }
    }
    return ans;
}

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