This documentation is automatically generated by online-judge-tools/verification-helper
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DSL_1_B"
#include "../../template/template.hpp"
#include "../../structure/union-find/weighted-union-find.hpp"
int main() {
int N, M;
cin >> N >> M;
WeightedUnionFind< int > tree(N);
while(M--) {
int A, B, C, D;
cin >> A >> B >> C;
if(A == 0) {
cin >> D;
tree.unite(B, C, D);
} else {
if(tree.find(B) == tree.find(C)) {
cout << tree.diff(B, C) << endl;
} else {
cout << "?" << endl;
}
}
}
}
#line 1 "test/verify/aoj-dsl-1-b.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DSL_1_B"
#line 1 "template/template.hpp"
#include<bits/stdc++.h>
using namespace std;
using int64 = long long;
const int mod = 1e9 + 7;
const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;
struct IoSetup {
IoSetup() {
cin.tie(nullptr);
ios::sync_with_stdio(false);
cout << fixed << setprecision(10);
cerr << fixed << setprecision(10);
}
} iosetup;
template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 >& p) {
os << p.first << " " << p.second;
return os;
}
template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
is >> p.first >> p.second;
return is;
}
template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
for(int i = 0; i < (int) v.size(); i++) {
os << v[i] << (i + 1 != v.size() ? " " : "");
}
return os;
}
template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
for(T &in : v) is >> in;
return is;
}
template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
template< typename T = int64 >
vector< T > make_v(size_t a) {
return vector< T >(a);
}
template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}
template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
t = v;
}
template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
for(auto &e : t) fill_v(e, v);
}
template< typename F >
struct FixPoint : F {
explicit FixPoint(F &&f) : F(forward< F >(f)) {}
template< typename... Args >
decltype(auto) operator()(Args &&... args) const {
return F::operator()(*this, forward< Args >(args)...);
}
};
template< typename F >
inline decltype(auto) MFP(F &&f) {
return FixPoint< F >{forward< F >(f)};
}
#line 4 "test/verify/aoj-dsl-1-b.test.cpp"
#line 1 "structure/union-find/weighted-union-find.hpp"
template< typename T >
struct WeightedUnionFind {
vector< int > data;
vector< T > ws;
WeightedUnionFind() {}
WeightedUnionFind(int sz) : data(sz, -1), ws(sz) {}
int find(int k) {
if(data[k] < 0) return k;
auto par = find(data[k]);
ws[k] += ws[data[k]];
return data[k] = par;
}
T weight(int t) {
find(t);
return ws[t];
}
bool unite(int x, int y, T w) {
w += weight(x);
w -= weight(y);
x = find(x), y = find(y);
if(x == y) return false;
if(data[x] > data[y]) {
swap(x, y);
w *= -1;
}
data[x] += data[y];
data[y] = x;
ws[y] = w;
return true;
}
T diff(int x, int y) {
return weight(y) - weight(x);
}
};
#line 6 "test/verify/aoj-dsl-1-b.test.cpp"
int main() {
int N, M;
cin >> N >> M;
WeightedUnionFind< int > tree(N);
while(M--) {
int A, B, C, D;
cin >> A >> B >> C;
if(A == 0) {
cin >> D;
tree.unite(B, C, D);
} else {
if(tree.find(B) == tree.find(C)) {
cout << tree.diff(B, C) << endl;
} else {
cout << "?" << endl;
}
}
}
}