59 lines
1.9 KiB
Java
59 lines
1.9 KiB
Java
import static java.lang.String.format;
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import java.util.Arrays;
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public class FloydWarshall {
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public static void main(String[] args) {
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int[][] weights = {{1, 3, -2}, {2, 1, 4}, {2, 3, 3}, {3, 4, 2}, {4, 2, -1}};
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int numVertices = 4;
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floydWarshall(weights, numVertices);
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}
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static void floydWarshall(int[][] weights, int numVertices) {
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double[][] dist = new double[numVertices][numVertices];
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for (double[] row : dist)
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Arrays.fill(row, Double.POSITIVE_INFINITY);
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for (int[] w : weights)
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dist[w[0] - 1][w[1] - 1] = w[2];
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int[][] next = new int[numVertices][numVertices];
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for (int i = 0; i < next.length; i++) {
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for (int j = 0; j < next.length; j++)
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if (i != j)
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next[i][j] = j + 1;
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}
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for (int k = 0; k < numVertices; k++)
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for (int i = 0; i < numVertices; i++)
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for (int j = 0; j < numVertices; j++)
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if (dist[i][k] + dist[k][j] < dist[i][j]) {
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dist[i][j] = dist[i][k] + dist[k][j];
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next[i][j] = next[i][k];
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}
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printResult(dist, next);
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}
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static void printResult(double[][] dist, int[][] next) {
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System.out.println("pair dist path");
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for (int i = 0; i < next.length; i++) {
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for (int j = 0; j < next.length; j++) {
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if (i != j) {
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int u = i + 1;
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int v = j + 1;
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String path = format("%d -> %d %2d %s", u, v,
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(int) dist[i][j], u);
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do {
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u = next[u - 1][v - 1];
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path += " -> " + u;
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} while (u != v);
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System.out.println(path);
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}
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}
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}
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}
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}
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