Submission #1022511

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022511		guagua0407	Tug of War (BOI15_tug)	C++17	23 / 100	117 ms	8156 KiB

tug

#pragma GCC optimize("O4,unroll-loops,no-stack-protector")
#pragma GCC target("avx,avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,fma")
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};

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

vector<vector<int>> adj,adjr;
vector<bool> vis;
vector<int> ord;
vector<int> scc;
vector<int> l,r,S;

bool comp(int a,int b){
    return S[a]<S[b];
}

void dfs(int v){
    vis[v]=true;
    for(auto u:adj[v]){
        if(vis[u]) continue;
        dfs(u);
    }
    ord.push_back(v);
}

void dfs2(int v,int id){
    scc[v]=id;
    vis[v]=true;
    for(auto u:adjr[v]){
        if(vis[u]) continue;
        dfs2(u,id);
    }
}

void addedge(int a,int b){
    adj[a].push_back(b);
    //cout<<a<<' '<<b<<'\n';
    adjr[b].push_back(a);
}

int main() {_
    auto st=clock();
    int n,k;
    cin>>n>>k;
    l.resize(2*n);
    r.resize(2*n);
    S.resize(2*n);
    int all=0;
    vector<vector<int>> ls(n),rs(n);
    for(int i=0;i<2*n;i++){
        cin>>l[i]>>r[i]>>S[i];
        l[i]--;
        r[i]--;
        ls[l[i]].push_back(i);
        rs[r[i]].push_back(i);
        all+=S[i];
    }
    adj.resize(4*n),adjr.resize(4*n);
    vis.resize(4*n);
    scc.resize(4*n);
    for(int i=0;i<n;i++){
        if(ls[i].empty() or rs[i].empty()){
            cout<<"NO"<<'\n';
            return 0;
        }
        for(auto a:ls[i]){
            for(auto b:ls[i]){
                if(a!=b){
                    addedge(2*a,2*b+1);
                }
            }
        }
        for(auto a:rs[i]){
            for(auto b:rs[i]){
                if(a!=b){
                    addedge(2*a+1,2*b);
                }
            }
        }
    }
    for(int i=0;i<4*n;i++){
        if(!vis[i]){
            dfs(i);
        }
    }
    reverse(all(ord));
    fill(all(vis),false);
    int cnt=0;
    for(int i=0;i<4*n;i++){
        if(!vis[ord[i]]){
            dfs2(ord[i],cnt++);
        }
    }
    int sum=0;
    for(int i=0;i<2*n;i++){
        if(scc[i*2]==scc[i*2+1]){
            cout<<"NO"<<'\n';
            return 0;
        }
    }
    vector<vector<int>> sccs(cnt);
    for(int i=0;i<4*n;i++){
        sccs[scc[i]].push_back(i);
    }
    fill(all(vis),false);
    vector<int> cand;
    int init=0;
    for(int i=0;i<cnt;i++){
        if(vis[sccs[i][0]/2]) continue;
        int cur=0;
        int sum=0;
        for(auto v:sccs[i]){
            if(v%2==0) cur+=S[v/2];
            sum+=S[v/2];
            vis[v/2]=true;
        }
        init+=cur;
        cand.push_back((sum-cur)-cur);
    }
    bitset<600005> b;
    b[init]=1;
    for(auto v:cand){
        b|=(b<<v);
    }
    int ans=all/2;
    while((all-ans)-ans<=k){
        if(b[ans]){
            cout<<"YES"<<'\n';
            return 0;
        }
        ans--;
    }
    cout<<"NO"<<'\n';
    return 0;
}
//maybe its multiset not set
//yeeorz
//laborz

Compilation message (stderr)

tug.cpp: In function 'int main()':
tug.cpp:55:10: warning: unused variable 'st' [-Wunused-variable]
   55 |     auto st=clock();
      |          ^~
tug.cpp:107:9: warning: unused variable 'sum' [-Wunused-variable]
  107 |     int sum=0;
      |         ^~~
tug.cpp: In function 'void setIO(std::string)':
tug.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tug.cpp:17:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 30
• Subtask 3: 23 / 23
• Subtask 4: 0 / 29