【递归】n个数的集合的所有子集

输入:

3

1 2 3

输出:

1

1 2

1 2 3

1 3

2

2 3

3

Delphi代码：

program full_combination;

const
  max_n = 10;

var
  n: integer;
  rcd, num: array[0..max_n] of integer;

procedure full_combination(index, p: integer);
var
  i: integer;
begin
  //每次都输出
  if index > 0 then
  begin
    for i := 0 to index - 2 do
      Write(rcd[i], ' ');
    writeln(rcd[index - 1]);
  end;

  for i := p to n - 1 do
  begin
    rcd[index] := num[i];
    full_combination(index + 1, i + 1);
  end;
end;

var
  i: integer;
begin
  while not seekeof do
  begin
    readln(n);
    for i := 0 to n - 1 do
      Read(num[i]);
    full_combination(0, 0);
  end;
end.

C++代码：

#include <stdio.h>
#define MAX_N 10

int rcd[MAX_N], num[MAX_N];
int n;

void full_combination(int index, int p)
{
    int i;
    for (i=0; i<index; i++)
    {
        printf("%d", rcd[i]);
        if (i<index-1)
        {
            printf(" ");
        }
    }
    printf("\n");

    for (i=p; i<n; i++)
    {
        rcd[index] = num[i];
        full_combination(index+1, i+1);
    }
}

int read_data()
{
    int i;
    if (scanf("%d", &n)==EOF)
    {
        return 0;
    }
    for (i=0; i<n; i++)
    {
        scanf("%d", &num[i]);
    }
    return 1;
}

void main()
{
    while(read_data())
    {
        full_combination(0,0);
    }
}