Submission #292081

#	Time	Username	Problem	Language	Result	Execution time	Memory
292081		zoooma13	Highway Tolls (IOI18_highway)	C++14	51 / 100	216 ms	13904 KiB

highway

#include <bits/stdc++.h>
#include "highway.h"
using namespace std;

vector<vector <pair<int ,int>>> adj;

vector <pair<int ,int>> ver;
void dfs(int u ,int p=-1 ,int f=-1){
    for(auto&e : adj[u]) if(e.first != p)
        dfs(e.first ,u ,e.second);
    ver.push_back({u ,f});
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
    assert(U.size() == N-1);
    adj.resize(N);
    for(int i=0; i<N-1; i++){
        adj[U[i]].push_back({V[i] ,i});
        adj[V[i]].push_back({U[i] ,i});
    }

    int S ,T;
    long long emp = ask(vector<int>(N-1 ,0));

    ver.clear() ,dfs(0) ,ver.pop_back();
    int st = 0 ,en = N-1 ,mid;
    while(st <= en){
        mid = (st+en)>>1;
        vector <int> t(N-1 ,0);
        for(int i=st; i<=mid; i++)
            t[ ver[i].second ] = 1;
        if(ask(t) != emp)
            en = mid-1;
        else
            st = mid+1;
    }
    S = ver[st].first;
    ver.clear() ,dfs(S) ,ver.pop_back();
    st = 0 ,en = N-1 ,mid;
    while(st <= en){
        mid = (st+en)>>1;
        vector <int> t(N-1 ,0);
        for(int i=st; i<=mid; i++)
            t[ ver[i].second ] = 1;
        if(ask(t) != emp)
            en = mid-1;
        else
            st = mid+1;
    }
    T = ver[st].first;
    answer(S ,T);
}

Compilation message (stderr)

In file included from /usr/include/c++/9/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:33,
                 from highway.cpp:1:
highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:15:21: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   15 |     assert(U.size() == N-1);
      |            ~~~~~~~~~^~~~~~
highway.cpp:39:26: warning: right operand of comma operator has no effect [-Wunused-value]
   39 |     st = 0 ,en = N-1 ,mid;
      |                          ^

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31