Submission #329728

#TimeUsernameProblemLanguageResultExecution timeMemory
329728chenwzStations (IOI20_stations)C++14
100 / 100
1006 ms1140 KiB
#include "stations.h" #include <vector> using namespace std; typedef vector<int> IVec; void rec(int u, int fa, bool pre_order, int &clock, const vector<IVec>& G, IVec& L) { if (pre_order) L[u] = clock++; for (int i : G[u]) if (i != fa) rec(i, u, !pre_order, clock, G, L); if (!pre_order) L[u] = clock++; } IVec label(int n, int k, IVec u, IVec v) { IVec L(n); vector<IVec> G(n, IVec()); for (int i = 0; i < u.size(); i++) G[u[i]].push_back(v[i]), G[v[i]].push_back(u[i]); int clock = 0; rec(0, -1, true, clock, G, L); return L; } int find_next_station(int s, int t, IVec c) { if (c[0] > s) { // Case 1: node s is in pre_order level. // All the neighbors are higher than s. if (t < s) { // The target is smaller than the source. // The target is definitely not in this subtree, go to parent. return c.back(); } if (t > c.back()) { // The target is higher than the largest neighbor. // The target cannot be in this subtree, go to parent. return c.back(); } // The target is in this subtree. // Pick the smallest child that's at least the target. int next = 0; while (c[next] < t) next++; return c[next]; } // Case 2: node s is in the post_order level. if (t < c[0]) { // The target is smaller than the pre_order root c[0], // thus not in this subtree, go to the root. return c[0]; } if (t > s) { // The target is higher than this post_order value. // Thus it's not in this subtree, go to the root. return c[0]; } int next = c.size() - 1; while (c[next] > t) next--; return c[next]; }

Compilation message (stderr)

stations.cpp: In function 'IVec label(int, int, IVec, IVec)':
stations.cpp:16:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |   for (int i = 0; i < u.size(); i++)
      |                   ~~^~~~~~~~~~
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