实验3

task 1

程序源码：

#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);
}

程序运行：

每秒输出一个“hi，April~”，共输入十个。

task 2

程序源码：

#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;
    
    return p;
}

程序运行（加了一行代码前）：

程序运行（加了一行代码后）：

task2_2.c

程序源码：

#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;
}

程序运行：

 task 3

程序源码：

#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) {
    if (n == 1)
        return 1;
    if (n == 2)
        return 3;
    else
        return 2 * func(n - 1) + 1;
}

程序运行：

task 4

程序源码：

#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 == 0 || n == m || m == 0)
        return 1;
    else if (n < m)
        return 0;
    else
        return func(n - 1, m) + func(n - 1, m - 1);
}

程序运行：

task 5.1

程序源码：

#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 t, i;

    if (y < 0) {
        t = -y;}
    else { t = y; }

    double sum = 1;
    for (i = 1; i <= t; i++) {
        sum *= x;}

    if (y > 0) { 
        return sum; }
    else { 1.0 / sum; }
}

程序运行：

task 5.2

程序源码：

#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); }
}

程序运行：

task 6

程序源码：

#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 tot;

int main() {
    unsigned int n;
    while (scanf("%u", &n) != EOF) {
        tot = 0;
        hanoi(n, 'A', 'B', 'C');
        printf("一共移动了%d次\n", tot);}
    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) {
    tot ++;
    printf("%u:%c-->%c\n", n, from, to);
}

程序运行：

task 7

程序源码：

#include<stdio.h>
int is_prime(int x);

int main() {
    int i, n;
    while (scanf("%d", &n) != EOF) {
        for (i = 2; i <= n; i++) {
            if (!is_prime(i) || !is_prime(n - i))continue;
            printf("%d = %d + %d\n", n, i, n - i);
            break;
        }
    }
    return 0;
}

int is_prime(int x) {
    int i;
    for (i = 2; i *i<= x; i++) {
        if (x % i == 0) {
            return 0;}
        else { 
            return 1; }
    }
}

程序运行：

task 8

程序源码：

#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 t = 0, t1 = 0;
    while (s > 0) {
        int tmp = s % 10;
        s /= 10;
        if (tmp % 2 == 1)t1 = t1 * 10 + tmp;
    }
    while (t1 > 0) {
        t = t * 10 + (t1 % 10);
        t1 /= 10;
    }
    return t;
}

程序运行：