CODEWITHSUNDEEP
c++algorithmdata-structuresgraph
Sumit Jaiswal
Sumit Jaiswal

Reputation: 236

error in map with custom data structure as value

I am trying to define an undirected weighted graph with vertexes as a string but having trouble with adding edges. I tried this method with normal map<string, vector<int>> and it works fine but with map<string, vector<structure>> it doesn't work.

Here's my approach:

#include <bits/stdc++.h>
using namespace std;

class AdjListNode
{
    string v;
    int weight;
    public:
        AdjListNode(string _v, int _w){v = _v; weight = _w;}
        string getV(){return v;}
        int getWeight(){return weight;}
};

class Graph
{
    int V;
    map<string, vector<AdjListNode>> *mp;
    public:
        Graph(int V);
        void addedge(string u, string v, int weight);
};

Graph::Graph(int V)
{
    this->V = V;
    mp = new map<string, vector<AdjListNode>>[V];
}

void Graph::addedge(string u,string v,int weight)
{
    AdjListNode node1(v,weight);
    mp[u].push_back(node1);                //<-error here
    AdjListNode node2(u,weight);
    mp[v].push_back(node2);             
}

int main()
{
    int v = 9;
    Graph g(v);
    g.addedge("A","B",4);
    g.addedge("A","C",8);
    g.addedge("B","C",11);
    g.addedge("B","D",8);
    g.addedge("C","E",7);
    g.addedge("C","F",1);
    g.addedge("D","E",2);
    g.addedge("E","F",6);
    g.addedge("D","G",7);
    g.addedge("D","H",4);
    g.addedge("F","H",2);
    g.addedge("G","H",14);
    g.addedge("G","I",9);
    g.addedge("H","I",10);
}

Error that I got:

In member function 'void Graph::addedge(std::cxx11::string, std::cxx11::string, int)':
D:\c++\graph\custom_vertex_undirected_weighted.cpp:33:7: error: no match for 'operator[]' (operand types are 'std::map<std::cxx11::basic_string, std::vector >*' and 'std::cxx11::string {aka std::cxx11::basic_string}')
mp[u].push_back(node1);
^

What am I doing wrong?

Upvotes: 0

Views: 51

Answers (1)

prehistoricpenguin
prehistoricpenguin

Reputation: 6326

I think you have a mixed array with hashmaps, in your case std::unordered_map is enough. We don't need to use array of std::unordered_map or std::vector<std::unordered_map<std::string, AdjListNode>>.

Then the fixed code:

class Graph {
  int V;
  map<string, vector<AdjListNode>> mp;

 public:
  Graph(int V);
  void addedge(string u, string v, int weight);
};

Graph::Graph(int V) { this->V = V; }

void Graph::addedge(string u, string v, int weight) {
  AdjListNode node1(v, weight);
  mp[u].push_back(node1);
  AdjListNode node2(u, weight);
  mp[v].push_back(node2);
}

Online demo

Upvotes: 1

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