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Merged
pull merged 1 commit into from
Mar 23, 2026
Merged

[pull] master from williamfiset:master #132

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31 changes: 8 additions & 23 deletions src/main/java/com/williamfiset/algorithms/datastructures/unionfind/UnionFind.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,8 +27,8 @@ public class UnionFind {
// Used to track the size of each component
private int[] sz;

// id[i] points to the parent of i, if id[i] = i then i is a root node
private int[] id;
// parent[i] points to the parent of i, if parent[i] = i then i is a root node
private int[] parent;

// Tracks the number of components in the union find
private int numComponents;
Expand All @@ -43,10 +43,10 @@ public UnionFind(int size) {

this.size = numComponents = size;
sz = new int[size];
id = new int[size];
parent = new int[size];

for (int i = 0; i < size; i++) {
id[i] = i; // Link to itself (self root)
parent[i] = i; // Link to itself (self root)
sz[i] = 1; // Each component is originally of size one
}
}
Expand All @@ -59,25 +59,10 @@ public UnionFind(int size) {
* @return the root of the component containing p
*/
public int find(int p) {
int root = p;
while (root != id[root]) root = id[root];

// Path compression: point every node along the path directly to root
while (p != root) {
int next = id[p];
id[p] = root;
p = next;
}

return root;
if (p == parent[p]) return p;
return parent[p] = find(parent[p]);
}

// Alternative recursive formulation for find with path compression:
// public int find(int p) {
// if (p == id[p]) return p;
// return id[p] = find(id[p]);
// }

/** Returns true if elements p and q are in the same component. */
public boolean connected(int p, int q) {
return find(p) == find(q);
Expand Down Expand Up @@ -114,11 +99,11 @@ public void unify(int p, int q) {
// Merge smaller component into the larger one
if (sz[root1] < sz[root2]) {
sz[root2] += sz[root1];
id[root1] = root2;
parent[root1] = root2;
sz[root1] = 0;
} else {
sz[root1] += sz[root2];
id[root2] = root1;
parent[root2] = root1;
sz[root2] = 0;
}

Expand Down
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