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P19_Kruskal.cpp
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P19_Kruskal.cpp
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#include <bits/stdc++.h>
using namespace std;
// p3 really special subtree
typedef long long ll;
int parent[3000];
int size[3000];
int findParent(int i){
if (parent[i] != -1){
return findParent(parent[i]);
}
return i;
}
int unite(int i,int x){
if (size[x] > size[i]){
parent[i] = x;
size[x] += size[i];
return x;
}
else{
parent[x] = i;
size[i] += size[x];
return i;
}
}
int kruskals(int g_nodes, vector<int> g_from, vector<int> g_to, vector<int> g_weight) {
memset(parent,-1,sizeof(int) * (g_nodes+1));
memset(size,1,sizeof(int) * (g_nodes+1));
vector<vector<int>> edges;
for(int i=0;i<g_from.size();i++){
edges.push_back({g_weight[i],g_from[i],g_to[i]});
}
sort(edges.begin(),edges.end());
int mWeight =0;
// cout << edges.size() <<endl;
for(int i=0;i<edges.size();i++){
int p1 = findParent(edges[i][1]);
int p2 =findParent(edges[i][2]);
if ( p1 != p2 ){
int parent = unite(edges[i][1], edges[i][2]);
mWeight += edges[i][0];
if (size[parent] == g_nodes)break;
}
}
return mWeight;
}
int main()
{
cout << "Enter the nNodes nEdges and press Enter\n";
int nodes;
int edges;
cin >> nodes >> edges;
cout << "Enter each edge in format from to weight\n" ;
vector<int> from(edges);
vector<int> to(edges);
vector<int> weight(edges);
for(int i=0;i<edges;i++){
cin >> from[i] >> to[i] >> weight[i];
}
int res = kruskals(nodes,from, to ,weight);
cout << res <<endl;
return 0;
}