how to know if two vertexes are connected in graph c++
#include <bits/stdc++.h>
using namespace std;
// We can use dfs alrogithm.
// in this example, we have an vector 'graph' in which indexes are connected
// to each other, and an index of vertices we want to check if they are connected
// lets denote them as 'x' and 'y'
//NOTE THAT THIS ONLY WORKS ON NON-CYCLIC GRAPHS
bool dfs(int currIndx,int wantedIndx,vector<vector<int>> graph){
if(currIndx == wantedIndx)return true;
for(auto it : graph[currIndx]){
if(dfs(it,wantedIndx,graph)) return true;
}
return false;
}
int main(){
// Create connections
vector<int> Zero = {1,3};
vector<int> One = {2};
vector<int> Two = {4};
vector<int> Three = {1};
vector<int> Four = {0};
// now add them all to one graph
vector<vector<int>> graph(5);
graph[0] = Zero;
graph[1] = One;
graph[2] = Two;
graph[3] = Three;
graph[4] = Four;
// For this example lets check if 0 and 4 are somehow connected to each other
bool answer = dfs(0,4,graph);
if(answer == true)cout << "Yes, They Are Connected" << endl;
else cout << "NO, They Are Not Connected ;(" << endl;
}