Submission #67787

#	Time	Username	Problem	Language	Result	Execution time	Memory
67787		aquablitz11	Toy Train (IOI17_train)	C++14	23 / 100	446 ms	1968 KiB

train

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

const int N = 5e3+10;
vector<int> G[N], R[N];

vector<int> who_wins(vector<int> A, vector<int> C, vector<int> U, vector<int> V)
{
    // input
    int n = A.size();
    int m = U.size();
    for (int i = 0; i < m; ++i) {
        G[U[i]].push_back(V[i]);
        R[V[i]].push_back(U[i]);
    }

    vector<int> ans(n, 0);
    for (int i = 0; i < n; ++i) if (C[i]) { // i = main recharger we need for cycle
        // first step: find all nodes that can be forced to reach i
        vector<bool> reach(n, false);
        vector<int> cnt(n, 0);
        queue<int> Q;
        Q.push(i);
        reach[i] = true;
        while (!Q.empty()) {
            int u = Q.front(); Q.pop();
            for (auto p : R[u]) if (!reach[p]) {
                ++cnt[p];
                if ((A[p] && cnt[p] == 1) || (!A[p] && cnt[p] == G[p].size())) {
                    reach[p] = true;
                    Q.push(p);
                }
            }
        }
        // second step: find if i could be in cycle or not
        int cntr = 0;
        for (auto v : G[i]) if (reach[v]) ++cntr;
        if ((A[i] && cntr > 0) || (!A[i] && cntr == G[i].size())) {
            // third step: add all nodes that could reach the cycle to answer
            for (int i = 0; i < n; ++i) if (reach[i])
                ans[i] = 1;
        }
    }
    vector<int> cnt(n, 0);
    queue<int> Q;
    for (int u = 0; u < n; ++u) if (ans[u])
        Q.push(u);
    while (!Q.empty()) {
        int u = Q.front(); Q.pop();
        for (auto p : R[u]) if (!ans[p]) {
            ++cnt[p];
            if ((A[p] && cnt[p] == 1) || (!A[p] && cnt[p] == G[p].size())) {
                ans[p] = 1;
                Q.push(p);
            }
        }
    }

    return ans;
}

Compilation message (stderr)

train.cpp: In function 'std::vector<int> who_wins(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)':
train.cpp:30:63: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 if ((A[p] && cnt[p] == 1) || (!A[p] && cnt[p] == G[p].size())) {
train.cpp:39:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if ((A[i] && cntr > 0) || (!A[i] && cntr == G[i].size())) {
                                             ~~~~~^~~~~~~~~~~~~~
train.cpp:53:59: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if ((A[p] && cnt[p] == 1) || (!A[p] && cnt[p] == G[p].size())) {

• Subtask 1: 0 / 5
• Subtask 2: 0 / 10
• Subtask 3: 11 / 11
• Subtask 4: 0 / 11
• Subtask 5: 12 / 12
• Subtask 6: 0 / 51