69 lines
1.9 KiB
C#
69 lines
1.9 KiB
C#
public class Solution {
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private readonly int UNREACHABLE = 1_000_000_007;
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private int[,] MakeDistances(int n, int[][] edges) {
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var distances = new int[n, n];
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// Everything's unreachable at the beginning, except for self-loops
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for (var i = 0; i < n; ++i) {
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for (var j = 0; j < n; ++j) {
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distances[i, j] = UNREACHABLE;
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}
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distances[i, i] = 0;
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}
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// Process the edges
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foreach (int[] edge in edges) {
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var (u, v, weight) = (edge[0], edge[1], edge[2]);
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distances[u, v] = weight;
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distances[v, u] = weight;
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}
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return distances;
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}
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private void FloydWarshall(int n, int[,] distances) {
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for (int k = 0; k < n; ++k) {
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for (int i = 0; i < n; ++i) {
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for (int j = 0; j < n; ++j) {
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distances[i, j] = Math.Min(
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distances[i, j],
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distances[i, k] + distances[k, j]
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);
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}
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}
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}
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}
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private int FindWithFewestReachable(int n, int[,] distances, int threshold) {
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int foundCity = -1;
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int foundFewest = n;
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for (int i = 0; i < n; ++i) {
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int reachable = 0;
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for (int j = 0; j < n; ++j) {
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if (i == j) {
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continue;
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}
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if (distances[i, j] <= threshold) {
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++reachable;
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}
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}
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if (reachable <= foundFewest) {
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(foundCity, foundFewest) = (i, reachable);
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}
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}
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return foundCity;
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}
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public int FindTheCity(int n, int[][] edges, int distanceThreshold) {
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var distances = MakeDistances(n, edges);
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FloydWarshall(n, distances);
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return FindWithFewestReachable(n, distances, distanceThreshold);
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}
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}
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