http://uva.onlinejudge.org/external/105/10583.html
很簡單的Disjoint Set
最後輸出Case n: ans
C是大寫= = 害我WA了兩次
另外Uva真的是ANSI C..
註解只能用
/* This is a comment. */不能 用
// Not allowed in ANSI C害我吃了一次CE…

#include <stdio.h>

int group;  
int set[50001];  
int rank[50001];  
void set_init(int n)  
{  
 int i;  
 for (i = 1; i <= n; i++) {  
 set[i] = i;  
 rank[i] = 1;  
 }  
 return ;  
}  
int find(int x)  
{  
 if (set[x] == x) {  
 return x;  
 } else {  
 return set[x] = find(set[x]);  
 }  
}  
void unite(int a, int b)  
{  
 a = find(a);  
 b = find(b);  
 if (a == b) {  
 return ;  
 }  
 group--;  
 if (rank[a] < rank[b]) {  
 set[a] = b;  
 } else {  
 set[b] = a;  
 if (rank[a] == rank[b]) {  
 rank[a]++;  
 }  
 }  
}  
int main()  
{  
 int n, m, i, j, count = 0;  
 while (scanf("%d%d", &n, &m) != EOF && n && m) {  
 count++;  
 group = n;  
 set_init(n);  
 while (m--) {  
 scanf("%d%d", &i, &j);  
 unite(i, j);  
 }  
 printf("Case %d: %d\n", count, group);  
 }  
 return 0;  
}