HDU 1213 how many Tables (and collection)

How many TablesTime limit:2000/1000 MS (java/others) Memory limit:65536/32768 K (java/others)
Total submission (s): 14683 Accepted Submission (s): 7187


Problem descriptiontoday is Ignatius ' birthday. He invites a lot of friends. Now it ' s dinner time. Ignatius wants to know what many tables he needs at least. You has to notice that not all the friends know each of the other, and all the friends does not want to stay with strangers.

One important rule for this problem yes if I tell you A knows B, and b knows C, that means A, B, C know They can stay in one table.

For Example:if I-a knows B, B knows C, and D knows E, so A, B, C can stay in one table, and D, E has to stay in The other one. So Ignatius needs 2 tables at least.

Inputthe input starts with an integer T (1<=t<=25) which indicate the number of test cases. Then T test cases follow. Each test case is starts with the integers N and M (1<=n,m<=1000). N indicates the number of friends, the Friends is marked from 1 to N. Then M lines follow. Each line consists of integers a and B (a!=b), which means friend A and friend B know each other. There'll be a blank line between the cases.

Outputfor Each test case, just output how many tables Ignatius needs at least. Don't print any blanks.

Sample Input

25 31 22 34 55 12 5

Sample Output

24

Is the last number of guests to invite the table, and check set:

#include <iostream> #include <stdio.h> #include <string.h>using namespace Std;int pre[1010];int Union    _find (int node) {int leaf=node;    while (Node!=pre[node]) Node=pre[node];        while (leaf!=node) {int t_p=pre[leaf];        Pre[leaf]=node;    leaf=t_p; } return node;    int main (int argc, char *argv[]) {//Freopen ("1213.in", "R", stdin); int t;//test Case Quantity T (1<=t<=25) int n,m;//n Indicates the number of friends, the Friends is marked from 1 to N. Then M lines follow. Each line consists of integers a and B (a!=b), which means friend A and friend B know each other.    (1<=n,m<=1000) int A, B;    scanf ("%d", &t);        while (t--) {scanf ("%d%d", &n,&m);        memset (pre,0,sizeof (pre));        int total=n;        for (int i=1;i<=n;++i) pre[i]=i;            while (m--) {scanf ("%d%d", &a,&b);            int P=union_find (a);            int Q=union_find (b); if (p!=q) {pre[p]=q;            total--;    }} printf ("%d\n", total); } return 0;}

HDU 1213 how many Tables (and collection)