제출 #556002

#제출 시각아이디문제언어결과실행 시간메모리
556002iancu도시들 (IOI15_towns)C++14
49 / 100
19 ms916 KiB
#include "towns.h" #include <vector> using namespace std; int hubDistance(int N, int sub) { vector<vector<int>> dist(N, vector<int>(N, -1)); auto getDist = [&dist](int a, int b) { if (dist[a][b] == -1) dist[a][b] = dist[b][a] = getDistance(a, b); return dist[a][b]; }; int D1, D2, dist_max = 0; for (int i = 1; i < N; ++i) if (getDist(0, i) > dist_max) { dist_max = getDist(0, i); D1 = i; } dist_max = 0; for (int i = 0; i < N; ++i) if (i != D1 && getDist(D1, i) > dist_max) { dist_max = getDist(D1, i); D2 = i; } int R = getDist(D1, D2); for (int i = 0; i < N; ++i) if (i != D1 && i != 0) { int dist_i = (getDist(i, D1) - getDist(i, 0) + getDist(D1, 0)) / 2; R = min(R, max(dist_i, getDist(D1, D2) - dist_i)); } vector<int> leaves1, leaves2; int cnt1 = 0, cnt2 = 0; int st = 0, dr = 0; for (int i = 0; i < N; ++i) { int dist_i = (getDist(i, D1) - getDist(i, 0) + getDist(D1, 0)) / 2; if (R == max(dist_i, getDist(D1, D2) - dist_i)) { if (R == dist_i) { ++cnt1; leaves1.push_back(i); } else { ++cnt2; leaves2.push_back(i); } } else if (dist_i < getDist(D1, D2) - dist_i) { ++st; } else { ++dr; } } //if (dr == 0) // leaves2.push_back(D2); //else //++dr; if (st > N / 2 || dr > N / 2) return -R; vector<int> leaves; bool primul; if (leaves1.size() > leaves2.size()) { leaves = leaves1; primul = true; //if (st + leaves2.size() > N / 2) //return -R; } else { leaves = leaves2; primul = false; //if (dr + leaves1.size() > N / 2) // return -R; } auto sameSubtree = [&dist, &D1, &D2, &getDist](int a, int b, int _R) { int dist_lca = (getDist(a, D1) + getDist(b, D1) - getDist(a, b)) / 2; if (dist_lca <= _R) return false; return true; }; int candidat, ap = 0; for (auto i: leaves) if (ap == 0) { candidat = i; ap = 1; } else { if (primul) { if (sameSubtree(i, candidat, R)) ++ap; else --ap; } else { if (sameSubtree(i, candidat, getDist(D1, D2) - R)) ++ap; else --ap; } } ap = 0; for (auto i: leaves) if (primul) { if (sameSubtree(i, candidat, R)) ++ap; } else { if (sameSubtree(i, candidat, getDist(D1, D2) - R)) ++ap; } if (ap > N / 2) return -R; return R; }

컴파일 시 표준 에러 (stderr) 메시지

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:6:28: warning: unused parameter 'sub' [-Wunused-parameter]
    6 | int hubDistance(int N, int sub) {
      |                        ~~~~^~~
towns.cpp:9:15: warning: 'D1' may be used uninitialized in this function [-Wmaybe-uninitialized]
    9 |     if (dist[a][b] == -1)
      |               ^
towns.cpp:10:44: warning: 'D2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   10 |       dist[a][b] = dist[b][a] = getDistance(a, b);
      |                                 ~~~~~~~~~~~^~~~~~
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