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kruskal.cpp
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kruskal.cpp
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#include <bits/stdc++.h>
using namespace std;
#define N (int)1e5
int link[N];
int siz[N];
int find(int x){
while(x != link[x]) x = link[x];
return x;
}
void unite(int a, int b){
a = find(a);
b = find(b);
if (siz[a] < siz[b]) swap(a, b);
link[b] = a;
siz[a] += siz[b];
}
bool same(int a, int b){
return find(a) == find(b);
}
int main(){
for(int i = 0;i < N;i++){
link[i] = i;
siz[i] = 1;
}
vector<tuple<int, int, int>>edges;
edges.push_back(make_tuple(1, 2, 100));
edges.push_back(make_tuple(2, 3, 10));
edges.push_back(make_tuple(3, 4, 1));
edges.push_back(make_tuple(4, 1, 10));
edges.push_back(make_tuple(4, 2, 20));
sort(edges.begin(), edges.end(), [](tuple<int, int, int>a, tuple<int, int, int>b){
return get<2>(a) < get<2>(b);
});
int weight = 0;
for(auto e:edges){
int a = get<0>(e);
int b = get<1>(e);
int w = get<2>(e);
if (!same(a, b)){
weight += w;
unite(a, b);
}
}
cout << weight << endl;
return 0;
}