The Suspects
Description
Severe
acute respiratory syndrome (SARS), an atypical pneumonia of unknown
aetiology, was recognized as a global threat in mid-March 2003. To
minimize transmission to others, the best strategy is to separate the
suspects from others.
In the Not-Spreading-Your-Sickness University (NSYSU), there are
many student groups. Students in the same group intercommunicate with
each other frequently, and a student may join several groups. To
prevent the possible transmissions of SARS, the NSYSU collects the
member lists of all student groups, and makes the following rule in
their standard operation procedure (SOP).
Once a member in a group is a suspect, all members in the group are suspects.
However, they find that it is not easy to identify all the suspects
when a student is recognized as a suspect. Your job is to write a
program which finds all the suspects.
Input
The
input file contains several cases. Each test case begins with two
integers n and m in a line, where n is the number of students, and m is
the number of groups. You may assume that 0 < n <= 30000 and 0
<= m <= 500. Every student is numbered by a unique integer
between 0 and n?1, and initially student 0 is recognized as a suspect
in all the cases. This line is followed by m member lists of the
groups, one line per group. Each line begins with an integer k by
itself representing the number of members in the group. Following the
number of members, there are k integers representing the students in
this group. All the integers in a line are separated by at least one
space.
A case with n = 0 and m = 0 indicates the end of the input, and need not be processed.
Output
For each case, output the number of suspects in one line.
Sample Input
100 4
2 1 2
5 10 13 11 12 14
2 0 1
2 99 2
200 2
1 5
5 1 2 3 4 5
1 0
0 0
Sample Output
4
1
1
題意：
給出人數n和人數里的人群數m，同個群的人屬于一個集合。求與編號0的人同個集合的人數（包括0本身)
代碼入下：
#include<stdio.h>
#define?maxn?30000
int?father[maxn];
void?setFather(int?n)
{
????for?(int?i?=?0;?i?<?n;?i++)
????{
????????father[i]?=?-1;
????}
}
int?find(int?a)
{
????if?(father[a]?<?0)
????{
????????return?a;
????}
????return?father[a]?=?find(father[a]);
}
void?Union(int?a,?int?b)
{
????a?=?find(a),?b?=?find(b);
????if?(a?!=?b)
????{
????????if?(father[a]?<?father[b])
????????{
????????????father[a]?+=?father[b];
????????????father[b]?=?a;
????????}
????????else
????????{
????????????father[b]?+=?father[a];
????????????father[a]?=?b;
????????}
????}
}
int?main()
{
????int?i,?j,?n,?m,?a,?b,?v,?t;
????while?(1)
????{
????????scanf("%d%d",?&n,?&m);
????????if?(n?==?0?&&?m?==?0)
????????{
????????????break;
????????}
????????setFather(n);
????????for?(i?=?0;?i?<?m;?i++)
????????{
????????????scanf("%d%d",?&v,?&a);
????????????for?(j?=?1;?j?<?v;?j++)
????????????{
????????????????scanf("%d",?&b);
????????????????Union(a,?b);
????????????}
????????}
????????printf("%d\n",?father[find(0)]?*?(-1));
????}
????return?0;
}