#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#define endl "\n"
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
template<class T, class T2> inline bool chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline bool chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const ll mod = 1e9 + 7;
template<class T> inline void fix(T &x) {if(x >= mod | x <= -mod) {x %= mod;} if(x < 0) {x += mod;}}
#define out(x) cout << __LINE__ << ": " << (#x) << " = " << (x) << endl
//If we have an even cycle then we can add 1 on odd edges and -1 on even edges so the solutions stay the same. We can remove leaves one by one
const ll MAX_N = 1e5 + 10;
set<pair<ll, ll> > g[MAX_N];
ll ans[MAX_N], arr[MAX_N];
struct cmp {
bool operator ()(const ll &a, const ll &b) const {
if(g[a].size() == g[b].size()) {
return a < b;
}
return g[a].size() < g[b].size();
}
};
multiset<ll, cmp> pq;
void removeBranches() {
while(!pq.empty() && g[*(pq.begin())].size() == 1) {
ll curr = *(pq.begin()); pq.erase(pq.begin());
auto other = *(g[curr].begin());
pq.erase(other.first);
ans[other.second] = 2 * arr[curr];
arr[other.first] -= arr[curr];
g[other.first].erase({curr, other.second});
pq.insert(other.first);
}
}
int rret = 0;
void dfs(int x, int p, int start, int flag) {
rret += arr[x] * flag;
//cout << x << " " << p << " " << ans[x] << " " << rret << endl;
for(auto it : g[x]) {
if(it.first == p || it.first == start) {continue;}
dfs(it.first, x, start, -flag);
}
}
void removeCycle() {
if(pq.size() < 2) {return;}
auto now = pq.begin();
if(g[*now].size() > 2) {
cout << 0 << endl;
exit(0);
}
now = pq.end(); now --;
if(g[*now].size() > 2) {
cout << 0 << endl;
exit(0);
}
if(pq.size() % 2 == 0) {
cout << 0 << endl;
exit(0);
}
int curr = *(pq.begin());
dfs(curr, (*(g[curr].begin())).first, curr, 1);
rret /= 2;
auto sec = (g[curr].begin());
arr[curr] -= rret;
arr[(*sec).first] -= rret;
ans[(*sec).second] = rret;
pq.erase(curr);
pq.erase((*sec).first);
g[curr].erase(sec);
g[(*sec).first].erase({curr, (*sec).second});1
pq.insert(curr);
pq.insert((*sec).first);
//cout << curr << " " << (*sec).first << " " << rret << endl;
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
ll n, m;
cin >> n >> m;
if(m > n) {cout << 0 << endl; return 0;}
for(ll i = 1; i <= n; i ++) {
cin >> arr[i];
}
for(ll i = 0; i < m; i ++) {
ll a, b;
cin >> a >> b;
g[a].insert({b, i});
g[b].insert({a, i});
}
for(ll i = 1; i <= n; i ++) {
pq.insert(i);
}
removeBranches();
removeCycle();
removeBranches();
for(ll i = 0; i < m; i ++) {
cout << ans[i] << endl;
}
return 0;
}
Compilation message
pipes.cpp: In function 'void removeCycle()':
pipes.cpp:83:5: error: expected ';' before 'pq'
pq.insert(curr);
^~
pipes.cpp:83:20: warning: statement has no effect [-Wunused-value]
pq.insert(curr);
^
