Submission #361703

#	Time	Username	Problem	Language	Result	Execution time	Memory
361703		cuongdh1912	Highway Tolls (IOI18_highway)	C++14	0 / 100	49 ms	1464 KiB

highway

// moreflags=grader.cpp
// :(
#include "highway.h"
#if not LOCAL
#define NDEBUG
#endif
#include<cassert>
#include<vector>
#include<cstdint>
#include<algorithm>
#include <array>
#include <queue>
using namespace std;
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
    int M = (int)U.size();
    vector<int> w;
    w.resize(M, 0);
    const auto d = ask(w);
    int i = 0;
    // find the maximum of index where there is no shortest path has edge in 0..<i
    // therefore there must be an edge index i the shortest path have
    for (auto step = 1<<20; step>>=1;) {
        if (i + step < M) {
            w.assign(i+step, 1);
            w.resize(M, 0);
            if (d == ask(w)) {
                i += step;
            }
        }
    }
    struct Edge { int node, index;};
    
    vector<vector<Edge> > add(N);
    for (int j = 0; j < M; ++j) {
        int a = U[j]; int b = V[j];
        add[a].push_back({b, j});
        add[b].push_back({a, j});
    }
    
    
    array<vector<Edge>, 2> edges;
    edges[0].push_back({U[i], i});
    edges[1].push_back({V[i], i});
    vector<bool> visited(M, false);
    
    for (int j = 0; j < edges.size(); ++j) {
        // find maximum
        queue<int> q;
        q.push(edges[j][0].node);
        visited[edges[j][0].node] = true;
        while (q.size() > 0) {
            int v = q.front(); q.pop();
            
            for (auto e: add[v]) {
                if (!visited[e.node]) {
                    visited[e.node] = true;
                    q.push(e.node);
                    edges[j].push_back(e);
                }
            }
        }
    }
    
    int ans[2];
    for (int j = 0; j < edges.size(); ++j ) {
        int k = (int)edges[j].size();
        for (int step = 1<<20; step>>=1; ) {
            if (k - step > 0) {
                w.assign(M, 1);
                w[i] = 0;
                for (int l = 0; l < k - step; ++l) w[edges[j][l].index] = 0;
                for (int l = 0; l < edges[!j].size(); ++l ) w[edges[!j][l].index] = 0;
                if (d == ask(w)) {
                    k -= step;
                }
            }
        }
        ans[j] = edges[j][k-1].node;
    }
    answer(ans[0], ans[1]);
}

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:46:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::array<std::vector<find_pair(int, std::vector<int>, std::vector<int>, int, int)::Edge>, 2>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for (int j = 0; j < edges.size(); ++j) {
      |                     ~~^~~~~~~~~~~~~~
highway.cpp:65:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::array<std::vector<find_pair(int, std::vector<int>, std::vector<int>, int, int)::Edge>, 2>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |     for (int j = 0; j < edges.size(); ++j ) {
      |                     ~~^~~~~~~~~~~~~~
highway.cpp:72:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<find_pair(int, std::vector<int>, std::vector<int>, int, int)::Edge>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |                 for (int l = 0; l < edges[!j].size(); ++l ) w[edges[!j][l].index] = 0;
      |                                 ~~^~~~~~~~~~~~~~~~~~

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