实验三

试验任务一

源代码

#include <stdio.h>
#include<stdlib.h>
char score_to_grade(int score);
int main() {
int score;
char grade;
while(scanf("%d", &score) != EOF) {
grade = score_to_grade(score); 
printf("分数: %d, 等级: %c\n\n", score, grade);
}
return 0;
}
// 函数定义
char score_to_grade(int score) {
char ans;
switch(score/10) {
case 10:
case 9:ans = 'A'; break;
case 8:ans = 'B'; break;
case 7:ans = 'C'; break;
case 6:ans = 'D'; break;
default:ans = 'E';
}
system("pause");
return ans;
}

结果截屏

 问题

1.功能：根据输入的分数，将其转换为对应的等级制字符并返回     形参类型：整型     返回值类型：字符型

2.用双引号会存在类型不匹配，从而使运行出错     缺少break语句，从而导致case穿透

试验任务二

源代码

#include <stdio.h>
#include<stdlib.h>
int sum_digits(int n);
int main() {
int n;
int ans;
while(printf("Enter n: "), scanf("%d", &n) != EOF) {
ans = sum_digits(n);
printf("n = %d, ans = %d\n\n", n, ans);
}
system("pause");
return 0;
}
int sum_digits(int n) {
int ans = 0;
while(n != 0) {
ans += n % 10;
n /= 10;
}
system("pause");
return ans;
}

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问题

1.计算并返回一个整数n的各个数字之和

2.能 前者是迭代  后者是递归

试验任务三

源代码

#include <stdio.h>
#include<stdlib.h>
int power(int x, int n);   
int main() {
int x, n;
int ans;
while(printf("Enter x and n: "), scanf("%d%d", &x, &n) != EOF) {
ans = power(x, n);  
printf("n = %d, ans = %d\n\n", n, ans);
}
system("pause");    
return 0;
}
int power(int x, int n) {
int t;
if(n == 0)
return 1;
else if(n % 2)
return x * power(x, n-1);
else {
t = power(x, n/2);
return t*t;
}
}

 

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问题

1.递归计算x的n次幂

2.是递归函数

1，                                  n=0      

 x X power(x, n-1)，        n=2k-1

 (power(x,n/2))的平方，  n=2k

试验任务四

源代码

#include <stdio.h>
#include<stdlib.h>
int main() {
    int a, b, c;
    while (scanf("%d %d %d", &a, &b, &c) != EOF) {
        int result = classify_triangle(a, b, c);
        switch (result) {
            case 0:
                printf("不能构成三角形\n");
                break;
            case 1:
                printf("普通三角形\n");
                break;
            case 2:
                printf("等边三角形\n");
                break;
            case 3:
                printf("等腰三角形\n");
                break;
            case 4:
                printf("直角三角形\n");
                break;
            default:
                break;
        }
    }
    system("pause");
    return 0;
}
int classify_triangle(int a, int b, int c) {
    if (a + b <= c || a + c <= b || b + c <= a) {
        return 0;
    }
    if (a == b && b == c) {
        return 2;
    }
    if (a == b || a == c || b == c) {
        return 3;
    }
    if (a*a + b*b == c*c || a*a + c*c == b*b || b*b + c*c == a*a) {
        return 4;
    }
    return 1;
}

 

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试验任务五

源代码

1.迭代

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

 

2.递归

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

 

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试验任务六

源代码

#include <stdio.h>
#include<stdlib.h>
int gcd(int a, int b, int c);
int main() {
    int a, b, c;
    int ans;
    while(scanf("%d%d%d", &a, &b, &c) != EOF) {
        ans = gcd(a, b, c);  
        printf("最大公约数：%d\n\n", ans);
    }
    system("pause");
    return 0;
}
int gcd(int a, int b, int c) {
    int min_val;
    min_val = (a < b) ? ((a < c) ? a : c) : ((b < c) ? b : c);
    int i;
    for(i = min_val; i >= 1; i--) {
       if(a % i == 0 && b % i == 0 && c % i == 0) {
            return i;
        }
    }
    return 1;
}

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试验任务七

源代码

#include <stdio.h>
#include <stdlib.h>
void print_charman(int n);
int main() {
    int n;
    printf("Enter n: ");
    scanf("%d", &n);
    print_charman(n); 
    system("pause");
    return 0;
}
void print_charman(int n) {
    for (int k = 0; k < n; k++) {
        for (int i = 0; i < k; i++) {
            printf("   "); 
        }
        for (int i = 0; i < n - k; i++) {
            printf("O  ");
        }
        printf("\n");
          for (int i = 0; i < k; i++) {
            printf("   "); 
        }
        for (int i = 0; i < n - k; i++) {
            printf("<> ");
        }
        printf("\n");
        for (int i = 0; i < k; i++) {
            printf("   ");
        }
        for (int i = 0; i < n - k; i++) {
            printf("I I");
        }
        printf("\n");
    }
}

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