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




void makeset(vector<int>&parent){
  for(int i=0;i<parent.size();i++){
    parent[i]=i;
  }
  return;
}


int find(vector<int>&parent,int k){
  if(parent[k]!=k){
    parent[k]=find(parent,parent[k]);
  }
  return parent[k];
}
 
void onion(vector<int>& parent,vector<int>& rank,int root1,int root2){
    int r1=find(parent,root1);
    int r2=find(parent,root2);
    if(r1==r2){
      return;
    }
    if(rank[r1]>rank[r2]){
        parent[r2]=r1;
    }
    else{
      parent[r1]=r2;
      if(rank[r1]==rank[r2]){
        rank[r2]++;
      }
    }
    
}


bool cycle(vector<pair<int,int>>edges,int size){
  vector<int>parent(size);
  makeset(parent);
  vector<int>rank(size,0);
  for(int i=0;i<edges.size();i++){
    int root1=find(parent,edges[i].first);
    int root2=find(parent,edges[i].second);
    if(root1==root2){
      return true;
    }
    else
      onion(parent,rank,root1,root2);
    
  }
  return false;
}

void addedge(vector<pair<int,int>> &edges,vector<int> graph[],int i,int j){
  graph[i].push_back(j);
  graph[j].push_back(i);
  edges.push_back({i,j});
}

int main() 
{
    int v=6;
    vector<int> graph[v];
    vector<pair<int,int>>edges;
    
    addedge(edges,graph,0,1);
    addedge(edges,graph,0,2);
    addedge(edges,graph,1,3);
    addedge(edges,graph,2,3);
    addedge(edges,graph,3,4);
    addedge(edges,graph,4,5);
    
    
    
    
    if(cycle(edges,v)){
      cout<<"cycle_undi_ra_howle"<<endl;
    }
    else cout<<"no"<<endl;
    return 0;
}
by

C++ Online Compiler

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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}