Codeforces 1144D Deduction Queries 并查集

Deduction Queries

用并查集维护前缀的关系， 在同一个联通块内两两之间的异或值都是已知的。

每个点再维护一个和它当前父亲的异或值， 压缩路径的时候更新一下就好了。

#include<bits/stdc++.h>
#define LL long long
#define LD long double
#define ull unsigned long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ALL(x) (x).begin(), (x).end()
#define fio ios::sync_with_stdio(false); cin.tie(0);

using namespace std;

const int N = 5e5 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-8;
const double PI = acos(-1);

template<class T, class S> inline void add(T& a, S b) {a += b; if(a >= mod) a -= mod;}
template<class T, class S> inline void sub(T& a, S b) {a -= b; if(a < 0) a += mod;}
template<class T, class S> inline bool chkmax(T& a, S b) {return a < b ? a = b, true : false;}
template<class T, class S> inline bool chkmin(T& a, S b) {return a > b ? a = b, true : false;}


int q, tot;
map<int, int> Map;

int xorWithFa[N];
int fa[N];

int getRoot(int x) {
    if(x == fa[x]) return x;
    int preFa = fa[x];
    int nowFa = getRoot(fa[x]);
    xorWithFa[x] ^= xorWithFa[preFa];
    return fa[x] = nowFa;
}

int main() {
    for(int i = 1; i < N; i++) fa[i] = i;
    scanf("%d", &q);
    int ans = 0;
    while(q--) {
        int op; scanf("%d", &op);
        if(op == 1) {
             int l, r, x;
             scanf("%d%d%d", &l, &r, &x);
             l ^= ans; r ^= ans; x ^= ans;
             if(l > r) swap(l, r);
             l--;
             if(Map.find(l) == Map.end()) Map[l] = ++tot;
             if(Map.find(r) == Map.end()) Map[r] = ++tot;
             l = Map[l]; r = Map[r];
             int fal = getRoot(l);
             int far = getRoot(r);
             if(fal != far) {
                int xor1 = xorWithFa[l];
                int xor2 = xorWithFa[r];
                fa[far] = fal;
                xorWithFa[far] = xor1 ^ xor2 ^ x;
             }
        } else {
            int l, r;
            scanf("%d%d", &l, &r);
            l ^= ans; r ^= ans;
            if(l > r) swap(l, r);
            l--;
            if(Map.find(l) == Map.end() || Map.find(r) == Map.end()) {
                puts("-1");
                ans = 1;
            } else {
                l = Map[l]; r = Map[r];
                int fal = getRoot(l);
                int far = getRoot(r);
                if(fal != far) {
                    puts("-1");
                    ans = 1;
                } else {
                    ans = xorWithFa[l] ^ xorWithFa[r];
                    printf("%d
", ans);
                }
            }
        }
    }
    return 0;
}

/*
*/