用c语言编写(9)编写程序，先输入-一个需要组合的整数，再输入3个用来组合的整数，若可以组合(每个数字至少使用1次)，则输出所有组合的可能;若不存在组合，则输出无组合(10) 修改第9题的程序，对于有组合的搭配，只输出第1个组合(11)编写程序，假设30个学生的成绩都是50~100分，成绩随机生成，要求每行输出6个学生的成绩，并最后统计输出最高分、最低分和平均分(保留2位小数)(12)编写万年历程序，输入年、月，输出该月的日历表。输入年，输出该年的日历表。已知1900年1月1日是星期一

(9)代码如下：

#include <stdio.h>
#include <stdbool.h>

void printArray(int arr[], int n) {
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

void combination(int arr[], int n, int m, int result[], int pos) {
    if (m == 0) {
        printArray(result, pos);
        return;
    }
    for (int i = n - 1; i >= m - 1; i--) {
        result[m - 1] = arr[i];
        combination(arr, i, m - 1, result, pos + 1);
    }
}

int main() {
    int n, m;
    printf("请输入需要组合的整数：");
    scanf("%d", &n);
    printf("请输入用来组合的三个整数：");
    int arr[3];
    for (int i = 0; i < 3; i++) {
        scanf("%d", &arr[i]);
    }
    int result[3];
    for (int i = 1; i <= 3; i++) {
        combination(arr, 3, i, result, 0);
    }
    bool found = false;
    for (int i = 0; i < 3; i++) {
        if (n == arr[i]) {
            found = true;
            break;
        }
    }
    if (found) {
        printf("%d ", n);
    }
    for (int i = 1; i <= 3; i++) {
        combination(arr, 3, i, result, 0);
        for (int j = 0; j < i; j++) {
            if (n == arr[j]) {
                found = true;
                break;
            }
        }
        if (found) {
            printArray(result, i);
            break;
        }
    }
    if (!found) {
        printf("无组合\n");
    }
    return 0;
}

(10)修改后的代码如下：

#include <stdio.h>
#include <stdbool.h>

void printArray(int arr[], int n) {
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

void combination(int arr[], int n, int m, int result[], int pos, bool *found) {
    if (m == 0) {
        if (*found) {
            return;
        }
        printArray(result, pos);
        *found = true;
        return;
    }
    for (int i = n - 1; i >= m - 1; i--) {
        result[m - 1] = arr[i];
        combination(arr, i, m - 1, result, pos + 1, found);
    }
}

int main() {
    int n, m;
    printf("请输入需要组合的整数：");
    scanf("%d", &n);
    printf("请输入用来组合的三个整数：");
    int arr[3];
    for (int i = 0; i < 3; i++) {
        scanf("%d", &arr[i]);
    }
    int result[3];
    bool found = false;
    for (int i = 0; i < 3; i++) {
        if (n == arr[i]) {
            found = true;
            printf("%d\n", n);
            break;
        }
    }
    for (int i = 1; i <= 3; i++) {
        combination(arr, 3, i, result, 0, &found);
        if (found) {
            break;
        }
    }
    if (!found) {
        printf("无组合\n");
    }
    return 0;
}

(11)代码如下：

#include <stdio.h>
#include <stdbool.h>

void printArray(int arr[], int n) {
    for (int i = 0; i < n; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

void combination(int arr[], int n, int m, int result[], int pos, bool *found) {
    if (m == 0) {
        if (*found) {
            return;
        }
        printArray(result, pos);
        *found = true;
        return;
    }
    for (int i = n - 1; i >= m - 1; i--) {
        result[m - 1] = arr[i];
        combination(arr, i, m - 1, result, pos + 1, found);
    }
}

int main() {
    int n, m;
    printf("请输入需要组合的整数：");
    scanf("%d", &n);
    printf("请输入用来组合的三个整数：");
    int arr[3];
    for (int i = 0; i < 3; i++) {
        scanf("%d", &arr[i]);
    }
    int result[3];
    bool found = false;
    for (int i = 0; i < 3; i++) {
        if (n == arr[i]) {
            found = true;
            printf("%d\n", n);
            break;
        }
    }
    for (int i = 1; i <= 3; i++) {
        combination(arr, 3, i, result, 0, &found);
        if (found) {
            break;
        }
    }
    if (!found) {
        printf("无组合\n");
    }
    return 0;
}

(12)代码如下：

#include <stdio.h>
#include <stdbool.h>

bool isLeapYear(int year) {
    if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
        return true;
    } else {
        return false;
    }
}

int daysInMonth(int year, int month) {
    int days[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    if (month == 2 && isLeapYear(year)) {
        return 29;
    } else {
        return days[month - 1];
    }
}

int daysInYear(int year) {
    if (isLeapYear(year)) {
        return 366;
    } else {
        return 365;
    }
}

int daysFrom1900(int year, int month, int day) {
    int days = 0;
    for (int i = 1900; i < year; i++) {
        days += daysInYear(i);
    }
    for (int i = 1; i < month; i++) {
        days += daysInMonth(year, i);
    }
    days += day - 1;
    return days;
}

int main() {
    int year, month;
    printf("请输入年份：");
    scanf("%d", &year);
    printf("请输入月份：");
    scanf("%d", &month);
    int days = daysFrom1900(year, month, 1);
    int weekDay = (days + 1) % 7;
    printf("日 一 二 三 四 五 六\n");
    for (int i = 0; i < weekDay; i++) {
        printf("   ");
    }
    int daysOfMonth = daysInMonth(year, month);
    for (int i = 1; i <= daysOfMonth; i++) {
        printf("%2d ", i);
        if ((weekDay + i) % 7 == 0) {
            printf("\n");
        }
    }
    if ((weekDay + daysOfMonth) % 7 != 0) {
        printf("\n");
    }
    return 0;
}