#include <algorithm> #include <cstdio> #include <cstdlib> #include <vector> int n, m; std::vector<int> graph[500005]; int range_left[500005]; int range_right[500005]; long long int result; int DistanceBetweenPointAndRange(int point, int left, int right) { if (point <= left) { return left - point; } else if (right <= point) { return point - right; } return 0; } void Dfs(int w, int father) { if ((int) graph[w].size() == 1) { return; } std::vector<int> track_gauges; for (int son : graph[w]) { if (son != father) { Dfs(son, w); track_gauges.push_back(range_left[son]); track_gauges.push_back(range_right[son]); } } const int above_median = (int) track_gauges.size() / 2; const int below_median = above_median - 1; std::nth_element(track_gauges.begin(), track_gauges.begin() + below_median, track_gauges.end()); range_left[w] = track_gauges[below_median]; std::nth_element(track_gauges.begin(), track_gauges.begin() + above_median, track_gauges.end()); range_right[w] = track_gauges[above_median]; for (int son : graph[w]) { if (son != father) { result += DistanceBetweenPointAndRange(range_left[w], range_left[son], range_right[son]); } } } int main() { scanf("%d%d", &n, &m); for (int i = 1; i < n; i++) { int a, b; scanf("%d%d", &a, &b); graph[a].push_back(b); graph[b].push_back(a); } for (int i = 1; i <= m; i++) { scanf("%d", &range_left[i]); range_right[i] = range_left[i]; } if (n == 2) { result = abs(range_left[1] - range_left[2]); } else { Dfs(n, -1); } printf("%lld\n", result); return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 | #include <algorithm> #include <cstdio> #include <cstdlib> #include <vector> int n, m; std::vector<int> graph[500005]; int range_left[500005]; int range_right[500005]; long long int result; int DistanceBetweenPointAndRange(int point, int left, int right) { if (point <= left) { return left - point; } else if (right <= point) { return point - right; } return 0; } void Dfs(int w, int father) { if ((int) graph[w].size() == 1) { return; } std::vector<int> track_gauges; for (int son : graph[w]) { if (son != father) { Dfs(son, w); track_gauges.push_back(range_left[son]); track_gauges.push_back(range_right[son]); } } const int above_median = (int) track_gauges.size() / 2; const int below_median = above_median - 1; std::nth_element(track_gauges.begin(), track_gauges.begin() + below_median, track_gauges.end()); range_left[w] = track_gauges[below_median]; std::nth_element(track_gauges.begin(), track_gauges.begin() + above_median, track_gauges.end()); range_right[w] = track_gauges[above_median]; for (int son : graph[w]) { if (son != father) { result += DistanceBetweenPointAndRange(range_left[w], range_left[son], range_right[son]); } } } int main() { scanf("%d%d", &n, &m); for (int i = 1; i < n; i++) { int a, b; scanf("%d%d", &a, &b); graph[a].push_back(b); graph[b].push_back(a); } for (int i = 1; i <= m; i++) { scanf("%d", &range_left[i]); range_right[i] = range_left[i]; } if (n == 2) { result = abs(range_left[1] - range_left[2]); } else { Dfs(n, -1); } printf("%lld\n", result); return 0; } |