Submission #484700

#	Time	Username	Problem	Language	Result	Execution time	Memory
484700		idas	Pipes (BOI13_pipes)	C++17	90.93 / 100	449 ms	53200 KiB

pipes

#include <bits/stdc++.h>
#define FOR(i, begin, end) for(int i = (begin); i < (end); i++)
#define FAST_IO ios_base::sync_with_stdio(false); cin.tie(nullptr)
#define TSTS int ttt; cin >> ttt; while(ttt--) solve()
#define F first
#define S second
#define PB push_back
#define MP make_pair

using namespace std;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long double, long double> pff;
typedef map<int, int> mii;
typedef vector<int> vi;
typedef long double ld;
typedef long long ll;

const int INF=1e9, MOD=1e9+7;

void setIO()
{
    FAST_IO;
}

void setIO(string s)
{
    FAST_IO;
    freopen((s+".in").c_str(), "r", stdin);
    freopen((s+".out").c_str(), "w", stdout);
}

const int N=5e5+10;
int n, m;
ll c[N], non[N];
vi ad[N];
bool v[N], vc[N];
map<pii, ll> x;
map<int, pii> con;

queue<int> q;
void bfs()
{
    while(!q.empty()){
        int u=q.front(); q.pop();
        if(v[u]) continue;
        v[u]=true;
        int cn=0;
        for(auto it : ad[u]){
            if(!x.count({it, u})) cn++;
        }
        if(cn>=2){
            v[u]=false;
            continue;
        }
        int in=-1;
        ll sm=0;
        for(auto it : ad[u]){
            if(!x.count({it, u})) in=it;
            sm+=x[{it, u}];
        }
        q.push(in);
        x[{in, u}]=x[{u, in}]=2LL*c[u]-sm;
    }
}

int inn;
ll sm, all;
void dfs(int u)
{
    v[u]=true; vc[u]=true;
    if(inn&1){
        sm+=2*c[u]-non[u];
    }
    all+=2*c[u]-non[u];
    inn++;
    for(auto it : ad[u]){
        if(v[it]) continue;
        dfs(it);
    }
}

int in;

void getA()
{
    int l=-1;
    for(auto it : ad[in]){
        if(!v[it]){
            if(l==-1) l=it;
            else break;
        }
    }
    dfs(l);
    x[{in, l}]=x[{l, in}]=all/2-sm;
}

void build(int u)
{
    vc[u]=false;
    ll have=0;
    for(auto it : ad[u]){
        if(x.count({u, it})) have+=x[{u, it}];
    }
    for(auto it : ad[u]){
        if(!x.count({u, it})){
            x[{u, it}]=x[{it, u}]=2LL*c[u]-have;
        }
    }
    for(auto it : ad[u]){
        if(!vc[it]) continue;
        build(it);
    }
}

void getNon()
{
    FOR(i, 0, n)
    {
        if(!v[i]){
            for(auto it : ad[i]){
                if(v[it]){
                    non[i]+=x[{i, it}];
                }
            }
        }
    }
}

int main()
{
    setIO();
    cin >> n >> m;
    FOR(i, 0, n) cin >> c[i];
    FOR(i, 0, m)
    {
        int a, b; cin >> a >> b; a--; b--;
        ad[a].PB(b);
        ad[b].PB(a);
        con[i]={a, b};
    }
    if(n<m){
        cout << 0;
        return 0;
    }

    vi lf;
    FOR(i, 0, n) if(ad[i].size()==1) lf.PB(i);

    for(auto u : lf){
        q.push(u);
    }

    bfs();
    getNon();

    FOR(i, 0, n)
    {
        if(!v[i]){
            in=i;
        }
    }

    if(in==-1){
        FOR(i, 0, m)
        {
            cout << x[con[i]] << '\n';
        }
        return 0;
    }

    getA();
    build(in);

    FOR(i, 0, m)
    {
        cout << x[con[i]] << '\n';
    }
}

Compilation message (stderr)

pipes.cpp: In function 'void setIO(std::string)':
pipes.cpp:29:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |     freopen((s+".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp:30:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     freopen((s+".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 60.925925925925924 / 70