I try very hard, buts for now I dont know whats is wrong with my code, can somebody help please?

class Result {

private static class Graph {

     private final int size;

    private long nodes = 0;

    private final long costForRoad;

    private final long costForLibrary;

    private final int[][] cities;

    public Graph(int size, final long costForRoad, final long costForLibrary) {
        this.size = size;
        this.costForRoad = costForRoad;
        this.costForLibrary = costForLibrary;
        this.cities = new int[size][];
        for (int i = 0; i < size; i++) {
            this.cities[i] = new int[size];
        }
    }

    public void addEdge(
            final int origin,
            final int destiny
    ) {
        this.cities[origin-1][destiny-1] = 1;
        this.cities[destiny-1][origin-1] = 1;
    }

   public long calcCost() {
        long cost = 0;
        final boolean[] visited = new boolean[this.size];
        for (int i = 0; i < this.size; i++) {
            if(!visited[i]) {
                nodes = 0;
                this.dfs(i, visited);
                  if(nodes == 1) {
                    cost += nodes * costForLibrary;
                } else {
                    cost += (nodes - 1) * costForRoad + costForLibrary;
                }
            }
        }

        return cost;
    }

    private void dfs(
            final int vertex,
            final boolean[] visited
    ) {
        nodes += 1;
        visited[vertex] = true;
        for (int i = 0; i < this.cities[vertex].length; i++) {
            if(this.cities[vertex][i] == 1 && !visited[i]) {
                dfs(i, visited);
            }
        }
    }
}

/*
 * Complete the 'roadsAndLibraries' function below.
 *
 * The function is expected to return a LONG_INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. INTEGER c_lib
 *  3. INTEGER c_road
 *  4. 2D_INTEGER_ARRAY cities
 */

public static long roadsAndLibraries(int n, int c_lib, int c_road, List<List<Integer>> cities) {
// Write your code here
    if(c_lib < c_road) {
        return n * c_lib;
    }

    final Graph graph = new Graph(n, c_road, c_lib);
    for(List<Integer> connections : cities) {
        graph.addEdge(connections.get(0), connections.get(1));
    }
    return graph.calcCost();
}

}

with custom input 1 5 3 6 1 1 2 1 3 1 4 it returns an expected answer of 15 when infact its 9. ie c_lib = 6 c_road = 1 1 library + 3 roads = 9 not 15 1 libraries + 3 roads = 15

Compiler Message: Wrong Answer

Input (stdin) 1 5 3 6 1 1 2 1 3 1 4 Your Output (stdout) 9

Any ideas why my answer is wrong? 4 cities in one aglomeration, cost of library 6 and cost of road 1. It's simply one library (6) and 3 roads (3) what all gives 9. Do I misunderstand something, or hackerrank has a bug?

I tried this using C++ and came up with a DSU solution but it seems to not pass 6 test cases out of 13, can anyone help me with it?

include

using namespace std;

string ltrim(const string &); string rtrim(const string &); vector split(const string &);

/* * Complete the 'roadsAndLibraries' function below. * * The function is expected to return a LONG_INTEGER. * The function accepts following parameters: * 1. INTEGER n * 2. INTEGER c_lib * 3. INTEGER c_road * 4. 2D_INTEGER_ARRAY cities */

class Disjoint{ public: vectorsize,parent; Disjoint(int n){ size.resize(n+1,1); parent.resize(n+1,0); for(int i=0;i<=n;i++) parent[i]=i; }

int findUParent(int node){ if(node==parent[node]) return node; return parent[node]=findUParent(parent[node]); }

void unionBySize(int u, int v){ int ulp_u=findUParent(u); int ulp_v=findUParent(v); if(ulp_u==ulp_v) return; else if(size[ulp_u]>size[ulp_v]){ parent[ulp_v]=ulp_u; size[ulp_u]+=size[ulp_v]; } else{ parent[ulp_u]=ulp_v; size[ulp_v]+=size[ulp_u]; } } };

long roadsAndLibraries(int n, int c_lib, int c_road, vector> cities) { if(c_road>=c_lib) return static_cast(n)*c_lib; Disjoint d(n); // int n=cities.size(); // int m=cities[0].size(); int tot=0,city=0; unordered_setst; for(auto x:cities){ if(d.findUParent(x[0])!=d.findUParent(x[1])){ d.unionBySize(x[0],x[1]); tot+=c_road; } } for(int node=1;node<=n;node++) st.insert(d.findUParent(node)); city=st.size(); tot+=city*c_lib; return (long)tot; }

int main()

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