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Submission #118742

# Submission time Handle Problem Language Result Execution time Memory
118742 2019-06-19T14:56:00 Z someone_aa Highway Tolls (IOI18_highway) C++17
11 / 100
 1500 ms 36024 KB 
#include "highway.h"
#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define mp make_pair
using namespace std;
const int maxn = 100100;
int n, m;
vector<int>w;
vector<int>gs[maxn];
vector<pair<int,int> > g[maxn];

vector<int>gt[maxn];

int dist[maxn][2], parent[maxn][2];
bool visited[maxn];

ll dista;

map<pair<int,int>, int> ind;
int type[maxn];
vector<pair<int,int> > sta, stb;

void bfs(int u, int v) {
    visited[u] = visited[v] = true;
    queue<pair<int,int> > q;

    type[u] = 0;
    type[v] = 1;
    q.push(mp(u, 0));
    q.push(mp(v, 1));

    while(!q.empty()) {
        int curr = q.front().first;
        int currtype = q.front().second;
        q.pop();

        for(auto i:gs[curr]) {
            if(visited[i]) continue;
            visited[i] = true;
            type[i] = currtype;
            q.push(mp(i, currtype));

            if(currtype == 0) sta.pb(mp(min(curr, i), max(curr, i)));
            else stb.pb(mp(min(curr, i), max(curr, i)));
        }
    }

}

void preprocess() {
    sort( sta.begin(), sta.end() );
    sta.erase( unique( sta.begin(), sta.end() ), sta.end() );
    sort( stb.begin(), stb.end() );
    stb.erase( unique( stb.begin(), stb.end() ), stb.end() );
}


int solve(int root, int d) {
    // build bfs tree
    //memset(visited,false,sizeof(visited));
    //memset(parent,-1,sizeof(parent));

    vector<pair<int,int> > edges;
    if(d == 0) edges = sta;
    else edges = stb;

    for(auto i:edges) {
        gt[i.first].pb(i.second);
        gt[i.second].pb(i.first);
    }

    vector<int>v, v2;

    queue<int>q;
    q.push(root);

    visited[root] = true;
    parent[root][d] = -1;

    while(!q.empty()) {
        int curr = q.front();
        q.pop();

        v.pb(parent[curr][d]);
        v2.pb(curr);
        for(auto i:gt[curr]) {
            if(!visited[i]) {
                visited[i] = true;
                parent[i][d] = curr;
                dist[i][d] = dist[curr][d] + 1;
                q.push(i);
            }
        }
    }

    if(v.size() == 1) return v2[0];
    // perform binary search

    for(int i=0;i<v.size();i++) {
        if(v[i] == -1) continue; // root
        int cind = ind[mp(v[i], v2[i])];
        w[cind] = 1;
    }

    int li = 0, ri = v.size() - 1;

    while(li < ri) {
        int mid = (li + ri) / 2;

        // all before mid put them as low cost and other as high cost
        for(int i=0;i<=mid;i++) {
            if(v[i] == -1) continue; // root
            int cind = ind[mp(v[i], v2[i])];
            w[cind] = 0;
        }

        ll cdist = ask(w);
        for(int i=0;i<=mid;i++) {
            if(v[i] == -1) continue; // root
            int cind = ind[mp(v[i], v2[i])];
            w[cind] = 1;
        }

        if(cdist == dista) {
            ri = mid;
        }
        else {
            li = mid + 1;
        }
    }

    for(int i=0;i<v.size();i++) {
        if(v[i] == -1) continue; // root
        int cind = ind[mp(v[i], v2[i])];
        w[cind] = 0;
    }

    return v2[li];
}

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
    n = N; m = U.size();
    int li=0, ri=m-1;

    for(int i=0;i<m;i++) {
        ind[mp(U[i], V[i])] = ind[mp(V[i], U[i])] = i;
        gs[U[i]].pb(V[i]);
        gs[V[i]].pb(U[i]);

        g[U[i]].pb(mp(V[i], i));
        g[V[i]].pb(mp(U[i], i));

        w.pb(0);
    }

    dista = ask(w);
    while(li<ri) {
        int mid = (li+ri)/2;
        for(int i=li;i<=mid;i++) {
            w[i] = 1;
        }
        ll distb = ask(w);
        for(int i=li;i<=mid;i++) {
            w[i] = 0;
        }

        if(dista == distb) {
            li = mid + 1;
        }
        else {
            ri = mid;
        }
    }
    int x = li;
    int u = U[x], v = V[x];

    //cout<<u<<" "<<v<<"\n";

    bfs(u, v);
    preprocess();

    memset(visited,false,sizeof(visited));
    //cout<<"Ans: "<<xx<<" "<<yy<<"\n";
    answer(solve(u, 0), solve(v, 1));
}

Compilation message

highway.cpp: In function 'int solve(int, int)':
highway.cpp:100:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<v.size();i++) {
                 ~^~~~~~~~~
highway.cpp:133:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<v.size();i++) {
                 ~^~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 7464 KB Output is correct
2 Correct 8 ms 7416 KB Output is correct
3 Correct 8 ms 7416 KB Output is correct
4 Correct 9 ms 7400 KB Output is correct
5 Correct 8 ms 7416 KB Output is correct
6 Correct 8 ms 7416 KB Output is correct
7 Correct 9 ms 7460 KB Output is correct
8 Correct 8 ms 7416 KB Output is correct
9 Correct 9 ms 7416 KB Output is correct
10 Correct 8 ms 7416 KB Output is correct
11 Correct 9 ms 7396 KB Output is correct
12 Correct 9 ms 7464 KB Output is correct

Subtask #2
0 / 7.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 7672 KB Output is correct
2 Correct 69 ms 10436 KB Output is correct
3 Correct 1413 ms 34324 KB Output is correct
4 Execution timed out 1625 ms 34400 KB Time limit exceeded
5 Halted 0 ms 0 KB -

Subtask #3
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 39 ms 10312 KB Output is correct
2 Correct 83 ms 12968 KB Output is correct
3 Correct 113 ms 16064 KB Output is correct
4 Correct 449 ms 32500 KB Output is correct
5 Correct 329 ms 32356 KB Output is correct
6 Correct 738 ms 32560 KB Output is correct
7 Correct 358 ms 33564 KB Output is correct
8 Correct 526 ms 32048 KB Output is correct
9 Correct 353 ms 33200 KB Output is correct

Subtask #4
0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 7672 KB Output is correct
2 Correct 55 ms 10360 KB Output is correct
3 Correct 458 ms 28720 KB Output is correct
4 Correct 719 ms 34472 KB Output is correct
5 Correct 629 ms 34588 KB Output is correct
6 Correct 633 ms 34260 KB Output is correct
7 Correct 641 ms 34304 KB Output is correct
8 Correct 631 ms 34184 KB Output is correct
9 Correct 1172 ms 34456 KB Output is correct
10 Correct 989 ms 34448 KB Output is correct
11 Execution timed out 1632 ms 33640 KB Time limit exceeded
12 Halted 0 ms 0 KB -

Subtask #5
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 88 ms 10468 KB Output is correct
2 Correct 64 ms 10676 KB Output is correct
3 Execution timed out 1960 ms 35800 KB Time limit exceeded
4 Halted 0 ms 0 KB -

Subtask #6
0 / 31.0

# Verdict Execution time Memory Grader output
1 Correct 65 ms 10536 KB Output is correct
2 Correct 104 ms 10760 KB Output is correct
3 Correct 730 ms 35132 KB Output is correct
4 Incorrect 1104 ms 36024 KB Output is incorrect: {s, t} is wrong.
5 Halted 0 ms 0 KB -