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RedundantConnections.java
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RedundantConnections.java
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class Solution {
class Node {
int parent,rank;
Node(int p,int r) {
parent=p; rank=r;
}
}
List<Node> dsuf;
public int[] findRedundantConnection(int[][] edges) {
dsuf=new ArrayList<>();
for(int i=0;i<edges.length;i++)
dsuf.add(new Node(-1,0));
for(int[] edge: edges) {
int from=edge[0]-1,to=edge[1]-1;
if(find(from)!=find(to))
union(from,to);
else
return edge;
}
return new int[0];
}
int find(int i) {
if(dsuf.get(i).parent==-1)
return i;
return dsuf.get(i).parent=find(dsuf.get(i).parent);
}
void union(int from,int to) {
Node a=dsuf.get(find(from)),b=dsuf.get(find(to));
if(a.rank>b.rank)
b.parent=from;
else if(a.rank<b.rank)
a.parent=to;
else {
a.parent=to;
a.rank++;
}
}
}