This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "bits/stdc++.h"
using namespace std;
void abc() {cout << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
cout << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
while (l != r) cout << *l << " \n"[++l == r];
}
template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) {
return o >> a.first >> a.second;
}
template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) {
return o << '(' << a.first << ", " << a.second << ')';
}
template <typename T> ostream& operator << (ostream& o, vector<T> a) {
bool is = false;
for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;}
return o << '}';
}
#ifdef local
#define test(args...) abc("[" + string(#args) + "]", args)
#else
#define test(args...) void(0)
#endif
using ll = long long;
ll v[100005];
int deg[100005];
vector<pair<int, int>> adj[100005];
ll calc[500005];
bool seen[100005];
bool seen2[100005];
vector<int> ord;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("test.txt", "r", stdin);
// freopen("", "w", stdout);
int n, m; cin >> n >> m;
if (m > n) {
cout << 0 << endl;
return 0;
}
for (int i = 1; i <= n; i++) cin >> v[i];
for (int i = 1; i <= m; i++) {
int a, b; cin >> a >> b;
adj[a].push_back({b, i});
adj[b].push_back({a, i});
deg[a]++; deg[b]++;
}
queue<int> q;
for (int i = 1; i <= n; i++) {
if (deg[i] == 1) {
q.push(i);
}
}
while (!q.empty()) {
// deg 1
auto cur = q.front(); q.pop();
seen[cur] = true;
deg[cur] = 0;
for (auto to : adj[cur]) {
if (seen[to.first]) continue;
ll weight = v[cur];
v[to.first] -= weight;
calc[to.second] = weight;
if (--deg[to.first] == 1) {
q.push(to.first);
}
}
}
if (m == n - 1) {
for (int i = 1; i <= m; i++) {
cout << calc[i] * 2 << "\n";
}
return 0;
}
vector<int> left;
for (int i = 1; i <= n; i++) {
if (deg[i] == 2) left.push_back(i);
}
if (left.size() % 2 == 0) {
cout << 0 << endl;
return 0;
}
if (left.empty()) {
// wtf
cout << 0 << endl;
return 0;
}
int start = left.front();
ord.push_back(start);
seen2[start] = true;
int cur = start;
while (true) {
bool pushed = false;
for (auto nxt : adj[cur]) {
if (!seen2[nxt.first] && deg[nxt.first] == 2) {
cur = nxt.first;
pushed = true;
seen2[nxt.first] = true;
ord.push_back(nxt.first);
break;
}
}
if (!pushed) break;
}
// for (auto x : ord) cout << x << " ";
ll prev = 0;
for (int i = 0; i < ord.size() - 1; i++) {
// assum back ->0 is X
ll now = v[ord[i]] - prev;
prev = now;
}
ll x = (v[ord[0]] - prev) / 2;
// cout << x << endl;
ll orig = x;
for (int i = 0; i < ord.size() - 1; i++) {
for (auto nxt : adj[ord[i]]) {
if (nxt.first == ord[i + 1]) {
calc[nxt.second] = v[ord[i]] - x;
x = calc[nxt.second];
break;
}
}
}
for (auto nxt : adj[ord[0]]) {
if (nxt.first == ord.back()) {
calc[nxt.second] = orig;
break;
}
}
for (int i = 1; i <= m; i++) {
cout << calc[i] * 2 << "\n";
}
}
Compilation message (stderr)
pipes.cpp: In function 'int main()':
pipes.cpp:137:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
137 | for (int i = 0; i < ord.size() - 1; i++) {
| ~~^~~~~~~~~~~~~~~~
pipes.cpp:151:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
151 | for (int i = 0; i < ord.size() - 1; i++) {
| ~~^~~~~~~~~~~~~~~~
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