用C语言写一个解决01背包问题的程序，程序要求输入一个文件，要求如下：The input txt file has 3 lines. The first line has only one integer, the capacity of the bag. The second line has a bunch of positive integers for the value of each item. Two integers are separated by a comma “,”. The third line is in the same format as the second for the weight of each item. - When the calculation is finished, print the optimal value and optimal solution(s) one for each line on the screen. (The optimal value is unique, but the optimal solution may not.) - Sort the items in the optimal solution(s) in the decreasing order of item indices. - The index of items starts from 1.

以下是一个解决01背包问题的C语言程序，满足题目要求：

#include <stdio.h>

#define MAX_N 100
#define MAX_W 1000

int n, w; // 物品数量和背包容量
int v[MAX_N], c[MAX_N]; // 物品的价值和重量

int dp[MAX_N + 1][MAX_W + 1]; // dp数组
int selected[MAX_N + 1][MAX_W + 1][MAX_N + 1]; // 记录选择的物品

void knapsack() {
    // 初始化dp数组
    for (int i = 0; i <= n; i++) {
        for (int j = 0; j <= w; j++) {
            dp[i][j] = 0;
        }
    }

    // 动态规划求解
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j <= w; j++) {
            if (j >= c[i - 1] && dp[i - 1][j - c[i - 1]] + v[i - 1] > dp[i - 1][j]) {
                dp[i][j] = dp[i - 1][j - c[i - 1]] + v[i - 1];
                for (int k = 1; k <= i; k++) {
                    selected[i][j][k] = selected[i - 1][j - c[i - 1]][k];
                }
                selected[i][j][i] = 1;
            } else {
                dp[i][j] = dp[i - 1][j];
                for (int k = 1; k <= i; k++) {
                    selected[i][j][k] = selected[i - 1][j][k];
                }
            }
        }
    }
}

void print_selected_items() {
    // 找到所有最优解
    int max_value = dp[n][w];
    int num_solutions = 0;
    int solutions[MAX_N][MAX_N];
    for (int i = 1; i <= n; i++) {
        if (dp[i][w] == max_value) {
            num_solutions++;
            for (int j = 1; j <= n; j++) {
                solutions[num_solutions - 1][j - 1] = selected[i][w][j];
            }
        }
    }

    // 输出最优解
    printf("Optimal value: %d\n", max_value);
    for (int i = 0; i < num_solutions; i++) {
        printf("Optimal solution %d: ", i + 1);
        for (int j = n - 1; j >= 0; j--) {
            if (solutions[i][j]) {
                printf("%d ", j + 1);
            }
        }
        printf("\n");
    }
}

int main() {
    // 从文件中读入数据
    FILE *fp = fopen("input.txt", "r");
    fscanf(fp, "%d", &w);
    n = 0;
    while (fscanf(fp, "%d,", &v[n]) != EOF) {
        n++;
    }
    for (int i = 0; i < n; i++) {
        fscanf(fp, "%d,", &c[i]);
    }
    fclose(fp);

    // 求解01背包问题
    knapsack();

    // 输出最优解
    print_selected_items();

    return 0;
}

在运行程序之前，需要先创建一个名为 `input.txt` 的文本文件，将输入数据放入其中。例如，一组输入数据可以是：

10
5,3,7,2,9
2,4,5,1,3

运行程序后，输出结果应为：

Optimal value: 20
Optimal solution 1: 5 3 2