P1196 学习笔记

省流：带权并查集

题目传送门

带一个飞船与其所在列队头的距离就行了。

code

#include <bits/stdc++.h>
#define DEBUG
#define Ofile(s) freopen(s".in", "r", stdin), freopen (s".out", "w", stdout)
#define Cfile(s) fclose(stdin), fclose(stdout)
#define fast ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
using namespace std;

using ll = long long;
using ull = unsigned long long;
using lb = long double;

constexpr int mod = 998244353;
constexpr int maxn = 30005;

int t, x, y;
char opt;

int fa[maxn], front[maxn], siz[maxn];

int find(int x){
	if (x == fa[x])
		return x;
	int findx = find(fa[x]);
	front[x] += front[fa[x]];
	return fa[x] = findx; // 带权的话会有点长
}

void merge(int x, int y){
	int findx = find(x), findy = find(y);
	if (findx == findy)
		return;
	front[findx] += siz[findy];
	siz[findy] += siz[findx];
	siz[findx] = 0;
	fa[findx] = findy; // 带权的话会有点长
}

int main() {
	fast;
	cin >> t;
	for (int i = 1; i <= maxn - 5; i++)
		fa[i] = i, siz[i] = 1;
	while (t--){
		cin >> opt >> x >> y;
		if (opt == 'C')
			if (find(x) != find(y))
				cout << -1 << endl;
			else 
				cout << abs(front[x] - front[y]) - 1 << endl; // 输出距离，记得-1！！
		else
			merge(x, y);
	}
	return 0;
}