c - 打印 C 中 int 数组的所有递减组合

Question

我有一个 int 数组，我需要打印所有可能的从最大数字开始的递减组合。示例如下:

int array[MAX_LEN]={ 5 , 4 , 3 , 2 , 1 }

和预期输出:

5 , 4 , 3 , 2 , 1  
5 , 4 , 3 , 2   
5 , 4 , 3 , 1  
5 , 4 , 2 , 1  
5 , 3 , 2 , 1  
5 , 2 , 1  
.  
.  
5 , 1  
.  
.  
5  

有人可以给我建议吗？谢谢

Answer 1

这个问题可以表示为“对于 [4,3,2,1] 的每个 subsequence 打印 5，后跟子序列”

要查找所有子序列，您可以按照以下方式执行操作

findAllSubsequences(array) {
    if (array is empty)
        return an empty list

    result = new list

    head = array[0]      // 4
    tail = array[1...]   // [3, 2, 1]

    tailSubsequences = findAllSubsequences(tail)  // recurse on tail

    // Add all subsequences that don't include head
    // [3,2,1] [3,1] [2,1] ...
    result.addAll(tailSubsequences)

    // Add all subsequences that do include head
    // [4,3,2,1] [4,3,1] [4,2,1] ...
    for each subsequence s in tailSubsequences
        result.add(head concatenated with s)

    return result
}