poj 并查集高级应用——1703，2492，1988，1417

http://poj.org/problem?id=1703

*#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
using namespace std;
#define N 100005
int n, m;
int p[N];
int ranks[N];
void init() {
	for (int i = 1; i <= n; i++)
	{
		p[i] = i;
		ranks[i] = 0;
	}
}
int find(int x) {
	if (x != p[x]) {
		int temp = p[x];
		p[x] = find(p[x]);
		ranks[x] = (ranks[x] + ranks[temp]) % 2;
	}
	return p[x];
}
void build(int x, int y) {
	int xx = find(x);
	int yy = find(y);
	if (xx != yy)
	{
		ranks[yy] = (ranks[x] - ranks[y] + 3) % 2;
		p[yy] = xx;
	}
	
}
int t;
int main() {
	cin >> t;
	char temp;
	int x, y;
	for (int k = 0; k < t; k++)
	{
		scanf("%d%d", &n, &m);
		init();
		cin.get();
		for (int i = 0; i < m; i++) {
			scanf("%c%d%d", &temp, &x, &y);
			if (temp == 'A') {
				int xx = find(x);
				int yy = find(y);
				if (xx == yy) {
					if (ranks[x] == ranks[y]) {
						cout << "In the same gang." << endl;
					}
					else
					{
						cout << "In different gangs." << endl;
					}
				}
				else
					cout << "Not sure yet." << endl;
			}
			else
			{
				build(x, y);
			}
			cin.get();
		}
	}
	return 0;
}

http://poj.org/problem?id=2492

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#define N 2005
using namespace std;
int n, m;
int p[N];
int ranks[N];
void init() {
	for (int i = 1; i <= n; i++)
	{
		p[i] = i;
		ranks[i] = 0;
	}
}
int find(int x) {
	if (x != p[x]) {
		int temp = p[x];
		p[x] = find(p[x]);
		ranks[x] = (ranks[x] + ranks[temp]) % 2;
	}
	return p[x];
}
int main()
{
	int t;
	int ans = 1;
	scanf("%d", &t);
	while (t--) {
		scanf("%d%d", &n, &m);
		init();
		int x, y;
		int flag = 1;
		for (int i = 0; i < m; i++)
		{
			scanf("%d%d", &x, &y);
			int xx = find(x);
			int yy = find(y);
			if (flag == 0)continue;
			if (xx == yy)
			{
				if (ranks[x] == ranks[y]) {
					flag = 0;
				}
			}
			else
			{
				p[yy] = xx;
				ranks[yy] = (ranks[x] - ranks[y] + 1) % 2;
			}
		}
		if (flag == 1)
		{
			cout << "Scenario #" << ans++ << ":" << endl;
			cout << "No suspicious bugs found!" << endl << endl;
		}
		else
		{
			cout << "Scenario #" << ans++ << ":" << endl;
			cout << "Suspicious bugs found!" << endl << endl;
		}
	}
	return 0;
}

http://poj.org/problem?id=1988

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<string>
using namespace std;
#define N 30005
int uset[N];
int dist[N];
int n;
int find(int x) {
	if (uset[x] < 0)
		return x;
	int temp = uset[x];
	uset[x] = find(temp);
	dist[x] = (dist[x] + dist[temp]);
	return uset[x];
}
int main()
{
	memset(uset, -1, sizeof(uset));
	memset(dist, 0, sizeof(dist));
	char trag;
	int x, y;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> trag;
		if (trag == 'M') {
			cin >> x >> y;
			int a = find(x);
			int b = find(y);
			if (a != b)
			{
				dist[b] = -uset[a];
				uset[a] += uset[b];
				uset[b] = a;
			}
		}
		else
		{
			cin >> x;
			y = find(x);
			cout << (-uset[y]) - 1 - dist[x] << endl;
		}
	}
	return 0;
}

http://poj.org/problem?id=1417

并查集加dp

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<set>
#include<vector>
#include<queue>
#include<map>
#include<functional>
#define N 1005
using namespace std;
int n, p1, p2;
int p[N];
int ranks[N];
int bs[N];
int dp[N][N];
int bg[N][N];
int fs[N];
int ans = 1;
struct cmp {
	bool operator()(int x,int y) {
		return x > y;
	}
};
set<int> q;
map<int, int>Q;
int find(int x)
{
	if (x != p[x]) {
		int temp = p[x];
		p[x] = find(p[x]);
		ranks[x] = (ranks[x] + ranks[temp]) % 2;
	}
	return p[x];
}
void build(int x1, int x2, string trag)
{
	int xx = find(x1);
	int yy = find(x2);
	if (xx != yy) {
		p[yy] = xx;
		if (trag == "no")
			ranks[yy] = (ranks[x2] - ranks[x1] + 3) % 2;
		else
			ranks[yy] = (ranks[x2] - ranks[x1] + 2) % 2;
	}
}
void init()
{
	q.clear();
	Q.clear();
	memset(dp, 0, sizeof(dp));
	memset(bg, 0, sizeof(bg));
	ans = 1;
	for (int i = 1; i <= p1 + p2; i++) {
		p[i] = i;
		ranks[i] = 0;
	}
}
void inster(int x,int v) {
	if (q.count(x)) {
		bg[fs[x]][v]++;
	}
	else
	{
		bs[ans] = x;
		fs[x] = ans++;
		bg[fs[x]][v]++;
		q.insert(x);
	}
}
int main()
{
	priority_queue<int, vector<int>, cmp > ps;
	string trag;
	int x1, x2;
	while (1)
	{
		scanf("%d%d%d", &n, &p1, &p2);
		if (n == p1 && p1 == p2 && n == 0)
			break;
		init();
		for (int i = 0; i < n; i++)
		{
			scanf("%d%d", &x1, &x2);
			cin.get();
			cin >> trag;
			build(x1, x2, trag);
		}
		for (int i = 1; i <= p1 + p2; i++)
		{
			int f = find(i);
			inster(f, ranks[i]);
		}
		dp[0][0] = 1;
		for (int i = 1; i < ans; i++) {
			for (int j = 0; j <= p1; j++) {
				if (j >= bg[i][0])
					dp[i][j] = dp[i - 1][j - bg[i][0]];
				if(j>=bg[i][1])
					dp[i][j] += dp[i - 1][j - bg[i][1]];
			}
		}
		if (dp[ans - 1][p1] == 1) {
			int re = p1;
			for (int i = ans-1; i >= 1; i--) {
				if (dp[i-1][re - bg[i][0]] == dp[i][re])
				{
					re = re - bg[i][0];
					Q[bs[i]] = 0;
				}
				else
				if (dp[i-1][re - bg[i][1]] == dp[i][re])
				{
					re = re - bg[i][1];
					Q[bs[i]] = 1;
				}
			}
			for (int i = 1; i <= p1 + p2; i++) {
				int re = find(i);
				if (ranks[i] == Q[re])
				{
					ps.push(i);
				}
			}
			while (!ps.empty()) {
				cout << ps.top() << endl;
				ps.pop();
			}
			cout << "end" << endl;
		}
		else
			cout << "no" << endl;
	}
	return 0;
}