Submission #1187188

#	Time	Username	Problem	Language	Result	Execution time	Memory
1187188		hainam2k9	Graph (BOI20_graph)	C++20	100 / 100	422 ms	55348 KiB

Graph

#include <bits/stdc++.h>
#define tt cin.tie(0), cout.tie(0), ios_base::sync_with_stdio(0)
#define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
#define ll long long
#define ull unsigned long long
#define i128 __int128
#define db long double
#define sz(a) ((int)(a).size())
#define pb emplace_back
#define pf emplace_front
#define pob pop_back
#define pof pop_front
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define ins emplace
#define mp make_pair
using namespace std;
const int MOD = 1e9+7, MAXN = 1e5+5;
const string NAME = "";
int n,m,depth[MAXN],color[MAXN];
ll sum[MAXN];
db rs[MAXN];
bool ok[MAXN],vis[MAXN];
vector<pair<int,int>> adj[MAXN];
vector<pair<int,db>> v;
map<pair<int,int>,int> MP;
inline bool diff(db& a, db b){
    return abs(a-b)>1e-6;
}
pair<int,db> dfs(int u, int par, int sgn){
    color[u]=1;
    for(pair<int,int>& e : adj[u]){
        if(e.fi==par||color[e.fi]==2) continue;
        if(color[e.fi]==1){
            if((depth[u]-depth[e.fi]+1)&1){
                if(sgn>0) return {e.fi,(sum[u]-sum[e.fi]+e.se)/2.0};
                return {e.fi,(sum[e.fi]-sum[u]+e.se)/2.0};
            }
            if(sgn<0&&sum[u]-sum[e.fi]!=e.se) cout << "NO", exit(0);
            else if(sgn>0&&sum[e.fi]-sum[u]!=e.se) cout << "NO", exit(0);
        }else{
            depth[e.fi]=depth[u]+1, sum[e.fi]=sum[u]+sgn*e.se;
            pair<int,db> p = dfs(e.fi,u,-sgn);
            if(p.fi>0) return p;
        }
    }
    color[u]=2;
    return {0,0};
}
void dfs2(int u, ll sum, int sgn, vector<ll>& v){
    vis[u]=1;
    for(pair<int,int>& e : adj[u])
        if(!vis[e.fi]) v.pb(sum+sgn*e.se), dfs2(e.fi,sum+sgn*e.se,-sgn,v);
}
void Answer(int u, db val){
    if(ok[u]&&diff(rs[u],val)) cout << "NO", exit(0);
    ok[u]=1, rs[u]=val;
    queue<pair<int,db>> q;
    q.ins(u,val);
    while(!q.empty()){
        pair<int,db> p=q.front();
        q.pop();
        for(pair<int,int>& e : adj[p.fi]){
            if(!ok[e.fi]) ok[e.fi]=1, rs[e.fi]=e.se-p.se, q.ins(e.fi,rs[e.fi]);
            else if(diff(rs[e.fi],e.se-p.se)) cout << "NO", exit(0);
        }
    }
}
int main()
{
    tt;
    if(fopen((NAME + ".INP").c_str(), "r")) fo;
    cout << fixed << setprecision(6);
    cin >> n >> m;
    for(int i = 1; i<=m; ++i){
        int x,y,z;
        cin >> x >> y >> z;
        if(MP[{x,y}]==0){
            MP[{x,y}]=MP[{y,x}]=z;
            if(x==y) v.pb(x,z/2.0);
            else adj[x].pb(y,z), adj[y].pb(x,z);
        }else if(MP[{x,y}]!=z) cout << "NO", exit(0);
    }
    for(pair<int,db>& p : v)
        Answer(p.fi,p.se);
    for(int i = 1; i<=n; ++i)
        if(!ok[i]){
            pair<int,db> val=dfs(i,0,1);
            if(val.fi==0){
                vector<ll> v;
                dfs2(i,0,1,v), val.fi=i;
                if(!v.empty()){
                    sort(v.begin(),v.end());
                    if(sz(v)&1) val.se=v[sz(v)/2];
                    else{
                        if(v[sz(v)/2]<0) val.se=v[sz(v)/2];
                        else if(v[sz(v)/2-1]>0) val.se=v[sz(v)/2-1];
                        else val.se=0;
                    }

                }
            }
            Answer(val.fi,val.se);
        }
    cout << "YES\n";
    for(int i = 1; i<=n; ++i)
        cout << rs[i] << " ";
}

Compilation message (stderr)

Graph.cpp: In function 'int main()':
Graph.cpp:3:19: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |            ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Graph.cpp:74:45: note: in expansion of macro 'fo'
   74 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~
Graph.cpp:3:63: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |                                                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Graph.cpp:74:45: note: in expansion of macro 'fo'
   74 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~

• Subtask 1: 12 / 12
• Subtask 2: 17 / 17
• Subtask 3: 24 / 24
• Subtask 4: 42 / 42
• Subtask 5: 5 / 5