Quick Find

Author: hackfengJam

UnionFind/src/UF.java

@@ -0,0 +1,8 @@
+public interface UF {
+
+    int getSize();
+
+    boolean isConnected(int p, int q);
+
+    void unionElements(int p, int q);
+}

UnionFind/src/UnionFind1.java

@@ -0,0 +1,48 @@
+public class UnionFind1 implements UF {
+    private int[] id;
+
+    public UnionFind1(int size) {
+        id = new int[size];
+        for (int i = 0; i < id.length; i++) {
+            id[i] = i;
+        }
+    }
+
+    @Override
+    public int getSize() {
+        return id.length;
+    }
+
+    // 查找 元素p所对应的集合编号
+    private int find(int p) {
+        if (p < 0 && p >= id.length) {
+            throw new IllegalArgumentException("p is out of bound");
+        }
+        return id[p];
+    }
+
+
+    // 查看元素p和元素q是否所属一个集合
+    @Override
+    public boolean isConnected(int p, int q) {
+        return find(p) == find(q);
+    }
+
+    // 合并元素p和元素q所属的集合
+    @Override
+    public void unionElements(int p, int q) {
+        int pID = find(p);
+        int qID = find(q);
+
+        if (pID == qID) {
+            return;
+        }
+
+        for (int i = 0; i < id.length; i++) {
+            if (id[i] == pID) {
+                id[i] = qID;
+            }
+        }
+
+    }
+}