Submission #67724

#TimeUsernameProblemLanguageResultExecution timeMemory
67724aquablitz11Toy Train (IOI17_train)C++14
23 / 100
1050 ms26140 KiB
#include <bits/stdc++.h> #include "train.h" using namespace std; const int N = 5e5+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); while (!Q.empty()) { int u = Q.front(); Q.pop(); reach[u] = true; for (auto p : R[u]) if (!reach[p]) { ++cnt[p]; if ((A[p] && cnt[p] == 1) || (!A[p] && cnt[p] == G[p].size())) Q.push(p); } } // second step: find all nodes that are part of i-cycle vector<bool> cycle(n, false); fill(cnt.begin(), cnt.end(), 0); // use as vis array Q.push(i); cnt[i] = 1; while (!Q.empty()) { int u = Q.front(); Q.pop(); int cntr = 0; for (auto v : G[u]) if (reach[v]) ++cntr; if ((A[u] && cntr > 0) || (!A[u] && cntr == G[u].size())) { cycle[u] = true; for (auto v : G[u]) if (!cnt[v]) { cnt[v] = 1; Q.push(v); } } } // third step: find all nodes that could reach the cycle fill(cnt.begin(), cnt.end(), 0); for (int u = 0; u < n; ++u) if (cycle[u]) Q.push(u); while (!Q.empty()) { int u = Q.front(); Q.pop(); cycle[u] = true; ans[u] = true; for (auto p : R[u]) if (!cycle[p]) { ++cnt[p]; if ((A[p] && cnt[p] == 1) || (!A[p] && cnt[p] == G[p].size())) 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:43:54: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if ((A[u] && cntr > 0) || (!A[u] && cntr == G[u].size())) {
                                                 ~~~~~^~~~~~~~~~~~~~
train.cpp:61:63: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 if ((A[p] && cnt[p] == 1) || (!A[p] && cnt[p] == G[p].size()))
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