Submission #659225

#	Time	Username	Problem	Language	Result	Execution time	Memory
659225		Soul234	Pipes (BOI13_pipes)	C++14	87.04 / 100	165 ms	35384 KiB

pipes

#include<bits/stdc++.h>
using namespace std;

void DBG() { cerr << "]\n"; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << h; if(sizeof...(t)) cerr << ", ";
    DBG(t...);
}
#ifdef LOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif // LOCAL

#define FOR(i,a,b) for(int i = (a) ; i<(b) ; i++)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for(int i = (b)-1 ; i>=(a) ; i--)
#define R0F(i,a) ROF(i,0,a)
#define each(e,a) for(auto &e : (a))
#define sz(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pb push_back
#define tcT template<class T
#define nl "\n"
#define fi first
#define se second
#define int long long

using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
using str = string;
using db = long double;
tcT> using V = vector<T>;
tcT> using pqg = priority_queue<T,vector<T>,greater<T>>;

void setIO(string NAME = "") {
    cin.tie(0)->sync_with_stdio(0);
    if(sz(NAME)) {
        freopen((NAME + ".inp").c_str(),"r",stdin);
        freopen((NAME + ".out").c_str(),"w",stdout);
    }
}

tcT> bool ckmin(T&a, const T&b) {
    return b < a ? a=b,1 : 0; }
tcT> bool ckmax(T&a, const T&b) {
    return b > a ? a=b,1 : 0; }

const int MOD = 1e9 + 7;
const ll INF = 1e18;

const int MX = 5e5+5;

int N, M;

vi adj[MX];

int tin[MX], tt;

int deg[MX], val[MX];

pi eds[MX];
bool used[MX], vis[MX];

int ans[MX];

void dfs(int u, int p) {
    tin[u] = ++tt;
    each(id, adj[u]) if(!used[id]) {
        used[id] = true;
        int v = eds[id].fi ^ eds[id].se ^ u;
        if(tin[v]) {
            if((tin[v]-tin[u])&1) {
                cout << "0\n";
                exit(0);
            }
        }
        else {
            dfs(v, u);
        }
    }
}

vi lst, lstid;

ll sum = 0;

int src;

void dfsList(int u, int p) {
    lst.pb(u);
    vis[u] = 1;
    sum += val[u];
    each(id, adj[u]) {
        int v = u ^ eds[id].fi ^ eds[id].se;
        if(deg[v] == 2 && v != p) {
            if(!vis[v] || v == src) lstid.pb(id);
        }
        if(!vis[v] && deg[v] == 2) {
            dfsList(v, u);
            return;
        }
    }
}

void solve() {
    cin >> N >> M;
    FOR(i,1,N+1) cin >> val[i];
    F0R(i, M) {
        int u, v;
        cin >> u >> v;
        adj[u].pb(i);
        adj[v].pb(i);
        eds[i] = {u, v};
        deg[u]++;
        deg[v]++;
    }
    if(M > N) {
        cout << "0\n";
        return;
    }
    dfs(1, -1);
    queue<int> q;
    FOR(i,1,N+1) if(deg[i] == 1) {
        q.push(i);
    }
    memset(used, false, sizeof used);
    while(sz(q)) {
        int u = q.front(); q.pop();
        each(id, adj[u]) if(!used[id]) {
            used[id] = true;
            int v = eds[id].fi ^ eds[id].se ^ u;
            val[v] -= val[u];
            ans[id] = val[u];
            if(--deg[v] == 1) {
                q.push(v);
            }
        }
    }
    FOR(i,1,N+1) if(deg[i] == 2) {
        src = i;
        dfsList(i, -1);
        break;
    }
    sum /= 2;
    if(!lstid.empty()) {
        for(int i = 2; i<sz(lst); i += 2) {
            sum -= val[lst[i]];
        }
//        each(id, lstid) dbg(id);
//        dbg(sum);
        ans[lstid[0]] = sum;
        for(int i = 1; i<sz(lstid); i++) {
            ans[lstid[i]] = val[lst[i]] - ans[lstid[i-1]];
        }
    }
    F0R(i, M) {
        cout << 2*ans[i] << nl;
    }
}

signed main() {
    setIO();

    int t=1;
    //cin>>t;
    while(t-->0) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

pipes.cpp: In function 'void setIO(std::string)':
pipes.cpp:41:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |         freopen((NAME + ".inp").c_str(),"r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp:42:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |         freopen((NAME + ".out").c_str(),"w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 57.03703703703704 / 70