Submission #310598

#	Time	Username	Problem	Language	Result	Execution time	Memory
310598		Ruxandra985	Tug of War (BOI15_tug)	C++14	100 / 100	1085 ms	9752 KiB

tug

#include <bits/stdc++.h>
#define DIMN 30010
using namespace std;

int n;

int f[4 * DIMN] , gr[4 * DIMN];
vector <pair <int , int> > v[4 * DIMN];
deque <int> dq;

bitset <20 * DIMN> rcs;

void dfs (int nod , int &val){
    int i , vecin , cst;

    f[nod] = 1;

    for (i = 0 ; i < v[nod].size() ; i++){
        vecin = v[nod][i].first;
        cst = v[nod][i].second;

        if (f[vecin])
            continue;

        if (vecin > 2 * n && vecin <= 3 * n){ /// il bagi in a
            val += cst;
        }
        else if (vecin > 3 * n) { /// il bagi in b
            val -= cst;
        }

        dfs (vecin , val);

    }


}
int main()
{
    FILE *fin = stdin;
    FILE *fout = stdout;
    int k , i , x , y , z , a = 0 , b = 0 , nod , vecin , cst , val , sum = 0;
    fscanf (fin,"%d%d",&n,&k);
    for (i = 1 ; i <= 2 * n ; i++){
        fscanf (fin,"%d%d%d",&x,&y,&z);
        v[i].push_back(make_pair(2 * n + x , z));
        v[2 * n + x].push_back(make_pair(i , z));
        v[i].push_back(make_pair(3 * n + y , z));
        v[3 * n + y].push_back(make_pair(i , z));

        gr[2 * n + x]++;
        gr[3 * n + y]++;
    }

    for (i = 2 * n + 1 ; i <= 4 * n ; i++){
        if (gr[i] == 1){

            dq.push_back(i);

        }
    }

    while (!dq.empty()){

        nod = dq.front();
        dq.pop_front();

        f[nod] = 1; /// pozitia asta a fost luata

        for (i = 0 ; i < v[nod].size() ; i++){
            vecin = v[nod][i].first;
            cst = v[nod][i].second;
            if (!f[vecin]){

                f[vecin] = 1;
                if (nod <= 3 * n)
                    a += cst;
                else b += cst;

                nod = vecin;
                break;

            }
        }

        /// nod = omul

        for (i = 0 ; i < v[nod].size() ; i++){
            vecin = v[nod][i].first;
            gr[vecin]--;
            if (gr[vecin] == 1){
                dq.push_back(vecin);
            }
        }

    }

    /// faci ce este obligatoriu

    rcs[0] = 1;

    for (i = 1 ; i <= 2 * n ; i++){
        if (!f[i]){

            val = 0;
            dfs (i , val);

            /// val = o valoare a unui cuplaj din punctul asta

            val = max(val , -val);
            sum += val;

            rcs = (rcs | (rcs << val));
            ///rcs e un rucsac. rcs[i] = 1 inseamna ca exista o suma de idk cate
            ///cuplaje care da i (in modul toate)

        }
    }


    for (i = 1 ; i <= 4 * n ; i++){
        if (!f[i]){
            fprintf (fout,"NO");
            return 0;
        }
    }

    /// aleg un numar de cuplaje din astea si le iau valorile negative in loc
    /// de cele pozitive

    for (i = 0 ; i <= 20 * n ; i++){

        if (rcs[i] && max( (a - b + sum - 2 * i) , -(a - b + sum - 2 * i) ) <= k){
            fprintf (fout,"YES");
            return 0;
        }

    }

    fprintf (fout,"NO");

    return 0;
}

Compilation message (stderr)

tug.cpp: In function 'void dfs(int, int&)':
tug.cpp:18:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     for (i = 0 ; i < v[nod].size() ; i++){
      |                  ~~^~~~~~~~~~~~~~~
tug.cpp: In function 'int main()':
tug.cpp:70:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   70 |         for (i = 0 ; i < v[nod].size() ; i++){
      |                      ~~^~~~~~~~~~~~~~~
tug.cpp:88:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   88 |         for (i = 0 ; i < v[nod].size() ; i++){
      |                      ~~^~~~~~~~~~~~~~~
tug.cpp:43:12: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   43 |     fscanf (fin,"%d%d",&n,&k);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~
tug.cpp:45:16: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   45 |         fscanf (fin,"%d%d%d",&x,&y,&z);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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