URAL 1272 Non-Yekaterinburg Subway (查并集)

#include<stdio.h>

#define MAX_ISLANDS (10000 + 1)
#define MAX_TUNELS (12000 + 1)
#define MAX_BRIDGES (12000 + 1)

struct CONNECTION{
	int oneIsland;
	int anotherIsland;
};
CONNECTION connectionArray[MAX_TUNELS + MAX_BRIDGES];
int connectionNum;
int islands;
int tunels;
int bridges;
int belongTo[MAX_ISLANDS];

int findBelongTo(int island){
	if (island == belongTo[island])
		return island;
	belongTo[island] = findBelongTo(belongTo[island]);
	return belongTo[island];
}

int connect(int oneIsland, int anotherIsland){
	int oneBelongTo = findBelongTo(oneIsland);
	int anotherBelongTo = findBelongTo(anotherIsland);
	if (oneBelongTo != anotherBelongTo){
		belongTo[oneBelongTo] = anotherBelongTo;
		return 1;
	}
	return 0;
}

int main(){
	scanf("%d %d %d", &islands, &tunels, &bridges);

	int island;
	for (island = 1; island <= islands; island++)
		belongTo[island] = island;

	int oneIsland, anotherIsland;
	int tunel;
	for (tunel = 1; tunel <= tunels; tunel++){
		scanf("%d %d", &oneIsland, &anotherIsland);
		connect(oneIsland, anotherIsland);		
	}

	int minBridges = 0;
	int bridge;
	for (bridge = 1; bridge <= bridges; bridge++){
		scanf("%d %d", &oneIsland, &anotherIsland);
		if (connect(oneIsland, anotherIsland))
			minBridges++;
	}

	printf("%d", minBridges);
	return 0;
}