DSU

Author: pranavbharadwaj007

CSES-Problem-Set/graph/road-reparation.cpp

@@ -0,0 +1,58 @@
+#include<bits/stdc++.h>
+using namespace std;
+ #define int long long
+#define mod (int) (1e9+7);
+const int N=1e5+10;
+int parent[N];
+int sizet[N];
+int n,m;
+void make(int v){
+ parent[v]=v;
+ sizet[v]=1;
+}
+int find(int v){
+ if(parent[v]==v)return parent[v];
+  return parent[v]=find(parent[v]);
+}
+void Union(int a,int b){
+  a=find(a);
+  b=find(b);
+  if(a!=b){
+    if(sizet[a]<sizet[b]){
+      swap(a,b);
+    }
+    parent[b]=a;
+    sizet[a]+=sizet[b];
+  }
+}
+signed main() {
+cin>>n>>m;
+vector<pair<int,pair<int,int>>>vec;
+for(int i=0;i<m;i++){
+ int u,v,w;
+ cin>>u>>v>>w;
+ vec.push_back({w,{u,v}});
+}
+int ans=0;
+int cnt=0;
+for(int i=1;i<=n;i++)make(i);
+sort(vec.begin(),vec.end());
+for(auto &it:vec){
+  int wt=it.first;
+  int x=it.second.first;
+  int y=it.second.second;
+  if(find(x)==find(y))continue;
+  Union(x,y);
+  cnt++;
+ ans+=wt;
+}
+if(cnt==n-1){
+cout<<ans<<endl;
+}
+else{
+  cout<<"IMPOSSIBLE"<<endl;
+}
+
+ return 0;
+}
+