Solution.java

class Solution {
    private final int inf = 2000000000;

    public int[][] modifiedGraphEdges(
        int n, int[][] edges, int source, int destination, int target) {
        long d = dijkstra(edges, n, source, destination);
        if (d < target) {
            return new int[0][];
        }
        boolean ok = d == target;
        for (var e : edges) {
            if (e[2] > 0) {
                continue;
            }
            if (ok) {
                e[2] = inf;
                continue;
            }
            e[2] = 1;
            d = dijkstra(edges, n, source, destination);
            if (d <= target) {
                ok = true;
                e[2] += target - d;
            }
        }
        return ok ? edges : new int[0][];
    }

    private long dijkstra(int[][] edges, int n, int src, int dest) {
        int[][] g = new int[n][n];
        long[] dist = new long[n];
        Arrays.fill(dist, inf);
        dist[src] = 0;
        for (var f : g) {
            Arrays.fill(f, inf);
        }
        for (var e : edges) {
            int a = e[0], b = e[1], w = e[2];
            if (w == -1) {
                continue;
            }
            g[a][b] = w;
            g[b][a] = w;
        }
        boolean[] vis = new boolean[n];
        for (int i = 0; i < n; ++i) {
            int k = -1;
            for (int j = 0; j < n; ++j) {
                if (!vis[j] && (k == -1 || dist[k] > dist[j])) {
                    k = j;
                }
            }
            vis[k] = true;
            for (int j = 0; j < n; ++j) {
                dist[j] = Math.min(dist[j], dist[k] + g[k][j]);
            }
        }
        return dist[dest];
    }
}