70 lines
1.2 KiB
C++
70 lines
1.2 KiB
C++
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//find total number of Connected Components in a graph
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//implementation of dsu
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#include<bits/stdc++.h>
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#define ll long long int
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using namespace std;
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ll find(ll x,vector<ll>&p)
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{
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if(p[x]==x)
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return x;
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else
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return p[x]=find(p[x],p);
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}
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void merge(ll a,ll b,vector<ll>&r,vector<ll>&p)
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{
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ll s1=find(a,p);
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ll s2=find(b,p);
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if(s1!=s2)
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{
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if(r[s1]<r[s2])
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{
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p[s1]=s2;
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r[s2]+=r[s1];
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}
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else
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{
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p[s2]=s1;
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r[s1]+=r[s2];
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}
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}
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}
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int main()
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{
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int n,m;
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cin>>n>>m;//enter the number of vertices and number of edges
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vector<ll>r(n,0);
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vector<ll>p;
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for(int i=0;i<n;i++)
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{
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p.push_back(i);
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}
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for(int i=0;i<m;i++)
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{
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int u,v;
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cin>>u>>v;
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u--;
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v--;
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merge(u,v,r,p);
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}
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map<ll,ll>mp;
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for(int i=0;i<n;i++)
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{
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ll x=find(i,p);
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mp[x]++;
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}
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cout<<"Total Number of Connected Components are - ";
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cout<<mp.size();
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return 0;
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}
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//INPUT
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//5 3
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//1 2
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//2 3
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//4 5
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//OUTPUT
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//Total Number of Connected Components are - 2
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//TIME COMPLEXITY OF THE PROGRAM
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//O(V+E)
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//where V is number of vertices
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//E is number of edges
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