Submission #1279332

#	Time	Username	Problem	Language	Result	Execution time	Memory
1279332		luattapcode	Tug of War (BOI15_tug)	C++20	100 / 100	431 ms	36740 KiB

tug

/*The best way to get something done is to begin*/
#include     <bits/stdc++.h>
#define     ll long long
#define     int long long
#define     fr(i,a,b) for(int i=a;i<=b;i++)
#define     frd(i,a,b) for(int i=a;i>=b;i--)
#define     pb push_back
#define     fi first
#define     se second
#define     el '\n'
using namespace std;
template <class X, class Y> bool minimize(X &x, const Y &y) {if (x > y) {x = y;return true;} else return false;}
template <class X, class Y> bool maximize(X &x, const Y &y) {if (x < y) {x = y;return true;} else return false;}
/* Author: Huynh Quoc Luat */
/*Khai Bao*/
const long long inf=1e18;
const int oo=1e9;
const int LO=21;
const int CH=27;
const int N=6e5+5;
const int sm=1e9+7;
int n,k;
multiset <pair <int,int>> g[N];
queue <int> q;
//void add(int &x,const int &y){x+=y;if(x>=sm)x-=sm;}
//void sub(int &x,const int &y){x-=y;if(x<0)x+=sm;}

void read()
{
    cin >> n >> k;
    fr(i,1,2*n){
        int l,r,s;
        cin >> l >> r >> s;
        g[l].insert({n+r,s});
        g[n+r].insert({l,-s});
    }
}

namespace sub1
{
    int tot;
    bool check[N];
    bitset <N> possible;
    void dfs(int u){
        check[u]=1;
        if(g[u].empty()) return;
        int nxt=g[u].begin()->fi;
        int cost=g[u].begin()->se;
        tot+=cost;
        if(!check[nxt]){
            g[nxt].erase(g[nxt].find({u,-cost}));
            g[u].clear();
            dfs(nxt);
        }
    }
    void process()
    {
        fr(i,1,2*n){
            if(g[i].size()==1) q.push(i);
            if(g[i].size()==0){
                cout << "NO";
                return;
            }
        }
        while(!q.empty()){
            int cur=q.front();
            q.pop();
            if(!g[cur].size()){
                cout << "NO";
                return;
            }
            int nxt=g[cur].begin()->fi;
            int cost=g[cur].begin()->se;
            tot+=cost;
            g[cur].clear();
            g[nxt].erase(g[nxt].find({cur,-cost}));
            if(g[nxt].size()==1) q.push(nxt);
        }
        vector <int> items;
        if(tot) items.pb(abs(tot));
        fr(i,1,2*n){
            if(!check[i] and !g[i].empty()){
                tot=0;
                g[i].erase(g[i].begin());
                dfs(i);
                if(tot) items.pb(abs(tot));
            }
        }
        int sum=0;
        for(auto v:items) sum+=v;
        possible[0]=1;
        for(int v:items) possible |= possible << v;
        fr(i,0,sum){
            if(possible[i] and abs(2*i-sum)<=k){
                cout << "YES";
                return;
            }
        }
        cout << "NO";
    }
}
void time()    {cerr<< endl<<"Luattapcode: "<<clock()<<"ms"<<endl;}
main()
{
    ios_base::sync_with_stdio(NULL);cin.tie(NULL);cout.tie(NULL);
    #define TASK "qn"
    if(fopen(TASK".INP","r"))
    {
        freopen(TASK".INP", "r", stdin);
        freopen(TASK".OUT", "w", stdout);
    }
    int mtt=0;
    int test=1;
    if(mtt) cin>>test;
    while(test--)
    {
        read();
        sub1::process();
    }
    time();
    return 0;
}

Compilation message (stderr)

tug.cpp:103:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  103 | main()
      | ^~~~
tug.cpp: In function 'int main()':
tug.cpp:109:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  109 |         freopen(TASK".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
tug.cpp:110:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  110 |         freopen(TASK".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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