LottoSubmit: 260 Accepted:99Time Limit: 1000MS Memory Limit: 65536KDescription
In
the German Lotto you have to select 6 numbers from the set
{1,2,...,49}. A popular strategy to play Lotto - although it doesn't
increase your chance of winning - is to select a subset S containing k
(k>6) of these 49 numbers, and then play several games with choosing
numbers only from S. For example, for k=8 and S = {1,2,3,5,8,13,21,34}
there are 28 possible games: [1,2,3,5,8,13], [1,2,3,5,8,21],
[1,2,3,5,8,34], [1,2,3,5,13,21], ... [3,5,8,13,21,34].
Your job is to write a program that reads in the number k and the set S
and then prints all possible games choosing numbers only from S.
Input
The
input file will contain one or more test cases. Each test case consists
of one line containing several integers separated from each other by
spaces. The first integer on the line will be the number k (6 < k
< 13). Then k integers, specifying the set S, will follow in
ascending order. Input will be terminated by a value of zero (0) for k.
Output
For
each test case, print all possible games, each game on one line. The
numbers of each game have to be sorted in ascending order and separated
from each other by exactly one space. The games themselves have to be
sorted lexicographically, that means sorted by the lowest number first,
then by the second lowest and so on, as demonstrated in the sample
output below. The test cases have to be separated from each other by
exactly one blank line. Do not put a blank line after the last test
case.
Sample Input
7 1 2 3 4 5 6 7
8 1 2 3 5 8 13 21 34
0
Sample Output
1 2 3 4 5 6
1 2 3 4 5 7
1 2 3 4 6 7
1 2 3 5 6 7
1 2 4 5 6 7
1 3 4 5 6 7
2 3 4 5 6 7
1 2 3 5 8 13
1 2 3 5 8 21
1 2 3 5 8 34
1 2 3 5 13 21
1 2 3 5 13 34
1 2 3 5 21 34
1 2 3 8 13 21
1 2 3 8 13 34
1 2 3 8 21 34
1 2 3 13 21 34
1 2 5 8 13 21
1 2 5 8 13 34
1 2 5 8 21 34
1 2 5 13 21 34
1 2 8 13 21 34
1 3 5 8 13 21
1 3 5 8 13 34
1 3 5 8 21 34
1 3 5 13 21 34
1 3 8 13 21 34
1 5 8 13 21 34
2 3 5 8 13 21
2 3 5 8 13 34
2 3 5 8 21 34
2 3 5 13 21 34
2 3 8 13 21 34
2 5 8 13 21 34
3 5 8 13 21 34
Source
University of Ulm Internal Contest
这个题代码写得很糙，组建调试出来的，该怎么快速的写出递归代码呢？？？？？？？？？求助～
#include
int out[6], set[15];
void recursion(int filled, int now, int size)
{
int i;
if (6 == filled) /*已经填充了6个了，可以输出*/
{
for (i=0 ; i<5 ; i++)
{
printf("%d ", out[i]);
}
printf("%d\n", out[i]);
return;
}
if (6 - filled > size - now) /*剩余的数字已不够填充，所以结束这种情况*/
{
out[filled - 1] = 0; /*这一句是多余的，可以去掉了*/
return ;
}
for (i=now ; i {
out[filled] = set[i]; /*填充一个数字*/
recursion(filled + 1, i + 1, size);
out[filled] = 0; /*执行完递归，恢复到上一种状态*/
}
}
void out_lotto(int size)
{
int i = 0, rep;
rep = size - 6 + 1;
recursion(0, i, size);
}
int main(int argc, char *argv[])
{
int i, j = 0, k = 0;
while (scanf("%d", &k) && 0 != k)
{
if (0 != j)
printf("\n");
for (i=0 ; i {
scanf("%d", &set[i]);
}
out_lotto(k);
j++;
}
}
总结递归枚举函数的代码格式：
1.进行条件判断，不成立就return
2.创建循环，设置当前状态，在循环中递归该函数，然后恢复状态
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