Design Graph With Shortest Path Calculator

1import java.util.*;
2
3class Graph {
4    private int n;
5    private List<List<int[]>> adj;
6
7    public Graph(int n, int[][] edges) {
8        this.n = n;
9        this.adj = new ArrayList<>();
10        for (int i = 0; i < n; i++) {
11            adj.add(new ArrayList<>());
12        }
13        for (int[] edge : edges) {
14            adj.get(edge[0]).add(new int[]{edge[1], edge[2]});
15        }
16    }
17
18    public void addEdge(int[] edge) {
19        adj.get(edge[0]).add(new int[]{edge[1], edge[2]});
20    }
21
22    public int shortestPath(int node1, int node2) {
23        int[] dist = new int[n];
24        Arrays.fill(dist, Integer.MAX_VALUE);
25        dist[node1] = 0;
26        PriorityQueue<int[]> pq = new PriorityQueue<>(Comparator.comparingInt(a -> a[1]));
27        pq.offer(new int[]{node1, 0});
28
29        while (!pq.isEmpty()) {
30            int[] current = pq.poll();
31            int u = current[0];
32            int curDist = current[1];
33
34            if (u == node2) return curDist;
35            if (curDist > dist[u]) continue;
36
37            for (int[] neighbor : adj.get(u)) {
38                int v = neighbor[0];
39                int weight = neighbor[1];
40                if (dist[u] + weight < dist[v]) {
41                    dist[v] = dist[u] + weight;
42                    pq.offer(new int[]{v, dist[v]});
43                }
44            }
45        }
46        return -1;
47    }
48
49    public static void main(String[] args) {
50        int[][] edges = {{0, 2, 5}, {0, 1, 2}, {1, 2, 1}, {3, 0, 3}};
51        Graph graph = new Graph(4, edges);
52        System.out.println(graph.shortestPath(3, 2)); // Output: 6
53        System.out.println(graph.shortestPath(0, 3)); // Output: -1
54        graph.addEdge(new int[]{1, 3, 4});
55        System.out.println(graph.shortestPath(0, 3)); // Output: 6
56    }
57}

1#include <stdio.h>
2#include <stdlib.h>
3#include <limits.h>
4
5#define INF INT_MAX
6
7typedef struct {
8    int n;
9    int** dist;
10} Graph;
11
12Graph* createGraph(int n, int edges[][3], int edgesSize) {
13    Graph* graph = (Graph*)malloc(sizeof(Graph));
14    graph->n = n;
15    graph->dist = (int**)malloc(n * sizeof(int*));
16    for (int i = 0; i < n; i++) {
17        graph->dist[i] = (int*)malloc(n * sizeof(int));
18        for (int j = 0; j < n; j++)
19            graph->dist[i][j] = (i == j) ? 0 : INF;
20    }
21    for (int i = 0; i < edgesSize; i++) {
22        int u = edges[i][0];
23        int v = edges[i][1];
24        graph->dist[u][v] = edges[i][2];
25    }
26    for (int k = 0; k < n; k++) {
27        for (int i = 0; i < n; i++) {
28            for (int j = 0; j < n; j++) {
29                if (graph->dist[i][k] != INF && graph->dist[k][j] != INF)
30                    graph->dist[i][j] = (graph->dist[i][j] > graph->dist[i][k] + graph->dist[k][j]) ? graph->dist[i][k] + graph->dist[k][j] : graph->dist[i][j];
31            }
32        }
33    }
34    
35    return graph;
36}
37
38void addEdge(Graph* graph, int u, int v, int cost) {
39    graph->dist[u][v] = cost;
40    // Re-run Floyd-Warshall
41    for (int k = 0; k < graph->n; k++) {
42        for (int i = 0; i < graph->n; i++) {
43            for (int j = 0; j < graph->n; j++) {
44                if (graph->dist[i][k] != INF && graph->dist[k][j] != INF)
45                    graph->dist[i][j] = (graph->dist[i][j] > graph->dist[i][k] + graph->dist[k][j]) ? graph->dist[i][k] + graph->dist[k][j] : graph->dist[i][j];
46            }
47        }
48    }
49}
50
51int shortestPath(Graph* graph, int node1, int node2) {
52    if(graph->dist[node1][node2] == INF)
53        return -1;
54    return graph->dist[node1][node2];
55}
56
57int main() {
58    int edges[4][3] = {{0, 2, 5}, {0, 1, 2}, {1, 2, 1}, {3, 0, 3}};
59    Graph* graph = createGraph(4, edges, 4);
60    printf("%d\n", shortestPath(graph, 3, 2)); // Output: 6
61    printf("%d\n", shortestPath(graph, 0, 3)); // Output: -1
62    addEdge(graph, 1, 3, 4);
63    printf("%d\n", shortestPath(graph, 0, 3)); // Output: 6
64    
65    // Free the memory
66    for(int i = 0; i < graph->n; i++)
67        free(graph->dist[i]);
68    free(graph->dist);
69    free(graph);
70    return 0;
71}