Submission #885546

#	Time	Username	Problem	Language	Result	Execution time	Memory
885546		8pete8	Pipes (BOI13_pipes)	C++17	72.78 / 100	285 ms	48984 KiB

pipes

#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<limits.h>
#include <cassert>
#include<cmath>
#include<set>
#include<algorithm>
#include <iomanip>
#include<numeric> //gcd(a,b)
#include<bitset>
using namespace std;
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,int>
#define ppii pair<int,pii>
#define vi vector<int>
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define F(n) for(int i=0;i<n;i++)
#define lb lower_bound
#define ub upper_bound
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
#pragma GCC optimize ("03,unroll-loops")
using namespace std;
#define int long long
const int mod=1e9+7,mxn=5e5+5,lg=30,inf=1e18,minf=-1e18;
int ans[mxn+10],val[mxn+10],up[mxn+10],curval[mxn+10];
vector<pii>adj[mxn+10];
bitset<mxn+10>vis;
bool yes=false;
void solve(int cur,int p){
    if(vis[cur])return void(yes=true);
    vis[cur]=true;
    bool leaf=true;
    for(auto i:adj[cur])if(i.f!=p)leaf=false;
    if(leaf){
        ans[up[cur]]+=val[cur];
        curval[p]+=val[cur];
        return;
    }
    for(auto i:adj[cur]){
        if(i.f==p)continue;
        up[i.f]=i.s;
        solve(i.f,cur);
    }
    if(cur==1)return;
    ans[up[cur]]+=(val[cur]-curval[cur]);
    curval[p]+=(val[cur]-curval[cur]);
}
vector<ppii>path;
int deg[mxn+10],sum,cnt=0;
int start=1;
void solve2(int cur,int p){
    if(vis[cur])return;
    cnt++;
    sum+=(val[cur]-curval[cur])*((cnt%2)?1:-1);
    vis[cur]=true;
    for(auto i:adj[cur]){
        if(i.f==start&&i.f!=p)path.pb({i.s,{i.f,cur}});
        if(i.f==p||vis[i.f])continue;
        up[i.f]=i.s;
        path.pb({i.s,{i.f,cur}});
        solve2(i.f,cur);
    }
}
int32_t main(){
    int n,m;cin>>n>>m;
    for(int i=1;i<=n;i++)cin>>val[i];
    for(int i=0;i<m;i++){
        int a,b;cin>>a>>b;
        adj[a].pb({b,i});
        adj[b].pb({a,i});
    }
    if(m>n){
        cout<<0;
        return 0;
    }
    if(m==n-1){
        solve(1,-1);
        for(int i=0;i<m;i++)cout<<2*ans[i]<<'\n';
        return 0;
    }
    stack<int>st;
    for(int i=1;i<=n;i++){
        if(adj[i].size()==1)st.push(i);
        deg[i]=adj[i].size();
    }
    cnt=0;
    while(!st.empty()){
        vis[st.top()]=true;
        for(auto i:adj[st.top()]){
            if(vis[i.f])continue;
            deg[i.f]--;
            ans[i.s]+=val[st.top()];-curval[st.top()];
            curval[i.f]+=val[st.top()];-curval[st.top()];
            if(deg[i.f]==1)st.push(i.f);
        }
        st.pop();
        cnt++;
    }
    for(int i=1;i<=n;i++)if(!vis[i])start=i;
    if((n-cnt)%2==0){
        cout<<0;
        return 0;
    }
    cnt=0;
    solve2(start,-1);
    sum/=2;
    reverse(all(path));
    for(int i=0;i<path.size();i++){
        if(i==0){
            ans[path[i].f]+=sum;
            curval[path[i].s.f]+=sum;
            curval[path[i].s.s]+=sum;
        }
        else{
            ans[path[i].f]+=val[path[i].s.f]-curval[path[i].s.f];
            curval[path[i].s.f]+=val[path[i].s.f]-curval[path[i].s.f];
            curval[path[i].s.s]+=val[path[i].s.f]-curval[path[i].s.f];
        }
    }
    for(int i=0;i<m;i++)cout<<2*ans[i]<<'\n';
}

Compilation message (stderr)

pipes.cpp: In function 'int32_t main()':
pipes.cpp:103:37: warning: value computed is not used [-Wunused-value]
  103 |             ans[i.s]+=val[st.top()];-curval[st.top()];
      |                                     ^~~~~~~~~~~~~~~~~
pipes.cpp:104:40: warning: value computed is not used [-Wunused-value]
  104 |             curval[i.f]+=val[st.top()];-curval[st.top()];
      |                                        ^~~~~~~~~~~~~~~~~
pipes.cpp:119:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, std::pair<long long int, long long int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  119 |     for(int i=0;i<path.size();i++){
      |                 ~^~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 42.77777777777778 / 70