Submission #278690

#	Time	Username	Problem	Language	Result	Execution time	Memory
278690		HynDuf	Pipes (BOI13_pipes)	C++14	100 / 100	270 ms	18680 KiB

pipes

#include <bits/stdc++.h>

#define task "P"
#define all(v) (v).begin(), (v).end()
#define rep(i, l, r) for (int i = (l); i <= (r); ++i)
#define Rep(i, r, l) for (int i = (r); i >= (l); --i)
#define DB(X) { cerr << #X << " = " << (X) << '\n'; }
#define DB1(A, _) { cerr << #A << "[" << _ << "] = " << (A[_]) << '\n'; }
#define DB2(A, _, __) { cerr << #A << "[" << _ << "][" << __ << "] = " << (A[_][__]) << '\n'; }
#define DB3(A, _, __, ___) { cerr << #A << "[" << _ << "][" << __ << "][" << ___ << "] = " << (A[_][__][___]) << '\n'; }
#define PR(A, l, r) { cerr << '\n'; rep(_, l, r) DB1(A, _); cerr << '\n';}
#define SZ(x) ((int)(x).size())
#define pb push_back
#define eb emplace_back
#define pf push_front
#define F first
#define S second
#define by(x) [](const auto& a, const auto& b) { return a.x < b.x; } // sort(arr, arr + N, by(a));
#define next ___next
#define prev ___prev
#define y1 ___y1
#define left ___left
#define right ___right
#define y0 ___y0
#define div ___div
#define j0 ___j0
#define jn ___jn

using ll = long long;
using ld = long double;
using ull = unsigned long long;
using namespace std;
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ll> vl;
const int N = 1e5 + 2;
int n, m, dep[N], deg[N];
ll ans[5 * N], c[N];
vii g[N];
bool dfs(int u, int p)
{
    dep[u] = dep[p] + 1;
    for (ii v : g[u]) if (v.F != p && dep[v.F] && (dep[u] - dep[v.F]) % 2 == 1) return 1;
    for (ii v : g[u]) if (v.F != p && !dep[v.F] && dfs(v.F, u)) return 1;
    return 0;
}
int main()
{
#ifdef HynDuf
    freopen(task".in", "r", stdin);
    //freopen(task".out", "w", stdout);
#else
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
#endif
    cin >> n >> m;
    rep(i, 1, n)
    {
        cin >> c[i];
        c[i] <<= 1;
    }
    rep(i, 1, m)
    {
        int u, v;
        cin >> u >> v;
        g[u].eb(v, i);
        g[v].eb(u, i);
        deg[u]++;
        deg[v]++;
    }
    if (dfs(1, 0))
    {
        cout << 0;
        return 0;
    }
    vi st;
    rep(i, 1, n) if (deg[i] == 1) st.pb(i);
    while (!st.empty())
    {
        int u = st.back();
        st.pop_back();
        deg[u]--;
        for (ii v : g[u]) if (deg[v.F] >= 1 && !ans[v.S])
        {
            ans[v.S] = c[u];
            c[v.F] -= c[u];
            if (--deg[v.F] == 1) st.pb(v.F);
        }
    }
    rep(i, 1, n) if (deg[i] > 2)
    {
        cout << 0;
        return 0;
    }
    rep(i, 1, n) if (deg[i] == 2)
    {
        int u = i, lst = 0, cnt = 0;
        ll sum = 0;
        while (1)
        {
            for (ii v : g[u]) if (deg[v.F] == 2 && v.F != lst)
            {
                cnt++;
                if (cnt & 1) sum += c[u];
                else sum -= c[u];
                lst = u;
                u = v.F;
                break;
            }
            if (u == i) break;
        }
        ll lstc = sum / 2;
        u = i, lst = 0;
        while (1)
        {
            for (ii v : g[u]) if (deg[v.F] == 2 && v.F != lst)
            {
                ans[v.S] = c[u] - lstc;
                lstc = ans[v.S];
                lst = u;
                u = v.F;
                break;
            }
            if (u == i) break;
        }
        break;
    }
    rep(i, 1, m) cout << ans[i] << '\n';
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70