Submission #940254

#	Time	Username	Problem	Language	Result	Execution time	Memory
940254		Zero_OP	Network (BOI15_net)	C++14	0 / 100	0 ms	348 KiB

net

#include<bits/stdc++.h>

using namespace std;
using int64 = int64_t;

#define     REP(i, n) for(int i = 0, _n = n; i < _n; ++i)
#define    REPD(i, n) for(int i = n - 1; i >= 0; --i)
#define  FOR(i, l, r) for(int i = l, _r = r; i <= _r; ++i)
#define FORD(i, r, l) for(int i = r, _l = l; i >= _l; --i)
#define          left __left
#define         right __right
#define          prev __prev
#define          next __next
#define           div __div
#define            pb push_back
#define            pf push_front
#define         sz(v) (int)v.size()
#define      range(v) begin(v), end(v)
#define    compact(v) v.erase(unique(range(v)), end(v))
#define      debug(v) "[" #v " = " << (v) << "]"

template<typename T>
    bool minimize(T& a, const T& b){
        if(a > b){
            a = b;
            return true;
        }
        return false;
    }

template<typename T>
    bool maximize(T& a, const T& b){
        if(a < b){
            a = b;
            return true;
        }
        return false;
    }

template<int dimension, class T>
struct vec : public vector<vec<dimension - 1, T>> {
    static_assert(dimension > 0, "Dimension must be positive !\n");
    template<typename... Args>
    vec(int n = 0, Args... args) : vector<vec<dimension - 1, T>>(n, vec<dimension - 1, T>(args...)) {}
};

template<class T>
struct vec<1, T> : public vector<T> {
    vec(int n = 0, T val = T()) : vector<T>(n, val) {}
};

#define Zero_OP //turn off when submitting
#ifdef Zero_OP

void init(void);
void process(void);

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);

    #define task "antuvu"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }

    int T = 1; //cin >> T;
    while(T--) {
        init();
        process();
    }

    return 0;
}

const int MAX = 5e5 + 5;

int n, deg[MAX];

void init(){
    cin >> n;
    REP(i, n - 1){
        int u, v;
        cin >> u >> v;
        --u, --v;
        ++deg[u]; ++deg[v];
    }
}

void process(){
    vector<int> leaves;
    REP(i, n){
        if(deg[i] == 1){
            leaves.pb(i);
        }
    }

    int res = (sz(leaves) + 1) / 2;
    cout << res << '\n';
    REP(i, res){
        cout << leaves[i] + 1 << ' ' << 1 + leaves[sz(leaves) - 1 - i] << '\n';
    }
}

#endif

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:64:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   64 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37