Submission #120397

#	Time	Username	Problem	Language	Result	Execution time	Memory
120397		onjo0127	Highway Tolls (IOI18_highway)	C++11	100 / 100	594 ms	12456 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;

int n, M;
long long ori;
vector<pii> adj[90009];
vector<int> u, v;
int D[90009];

pii ebs() {
    int l = 0, r = M-1;
    while(l <= r) {
        if(l == r) return (pii){u[l], v[l]};
        int m = l+r >> 1;
        vector<int> W(M, 0);
        for(int i=0; i<=m; i++) W[i] = 1;
        if(ask(W) != ori) r = m;
        else l = m+1;
    }
    return (pii){u[r+1], v[r+1]};
}

int vbs(vector<int> S) {
    int K = S.size();
    int l = 0, r = K-1;
    while(l <= r) {
        if(l == r) return S[l];
        int m = l+r >> 1;
        vector<int> W(M, 0);
        for(int i=0; i<=m; i++) for(auto& it: adj[S[i]]) W[it.second] = 1;
        if(ask(W) != ori) r = m;
        else l = m+1;
    }
    return S[r+1];
}

vector<int> f(vector<int>& D, int root) {
    int c = 1;
    for(int i=0; i<n; i++) D[i] = 0;
    queue<int> que; que.push(root); D[root] = 1;
    while(que.size()) {
        int sz = que.size();
        while(sz--) {
            int now; now = que.front(); que.pop();
            for(auto& it: adj[now]) {
                if(!D[it.first]) {
                    D[it.first] = c+1;
                    que.push(it.first);
                }
            }
        }
        ++c;
    }
    vector<int> S;
    for(int i=0; i<n; i++) S.push_back(i);
    sort(S.begin(), S.end(), [&](int P, int Q) {return D[P] > D[Q];});
    return S;
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
    u = U; v = V;
    n = N; M = U.size();
    for(int i=0; i<M; i++) {
        adj[U[i]].push_back({V[i], i});
        adj[V[i]].push_back({U[i], i});
    }
    vector<int> W(M, 0); ori = ask(W);
    int al, be; tie(al, be) = ebs();
    vector<int> DA(N), DB(N);
    f(DA, al); f(DB, be);
    vector<int> AS, BS, CS;
    for(int i=0; i<N; i++) {
        if(DA[i] < DB[i]) AS.push_back(i);
        else BS.push_back(i);
    }
    sort(AS.begin(), AS.end(), [&](int X, int Y) {return DA[X] > DA[Y];});
    int P = vbs(AS);
    for(auto& it: BS) if(DB[it] == (ori / A) - DA[P] + 1) CS.push_back(it);
    sort(CS.begin(), CS.end(), [&](int X, int Y) {return DB[X] > DB[Y];});
    int Q = vbs(CS);
    answer(P, Q);
}

Compilation message (stderr)

highway.cpp: In function 'pii ebs()':
highway.cpp:16:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         int m = l+r >> 1;
                 ~^~
highway.cpp: In function 'int vbs(std::vector<int>)':
highway.cpp:30:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
         int m = l+r >> 1;
                 ~^~

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