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KDTree.java
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KDTree.java
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package com.algorithm.playground.data.structure;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
public class KDTree {
private KDNode root;
private int dimensions;
public KDTree(int dimensions) {
this.dimensions = dimensions;
}
private static void buildCatalogPrefix(StringBuilder builder, int level, Set<Integer> last) {
if (level == 1) {
builder.append(" ");
} else {
int l = level + 3 * level;
for (int i = 0; i < l; i++) {
int charLevel = i == 1 ? 1 : i / 4;
if (!last.contains(charLevel) && (i == 1 || (i > 6 && i % 4 == 0 && l - i > 3))) {
builder.append("|");
} else {
builder.append(" ");
}
}
}
String tmp = builder.toString();
builder.append("|\n").append(tmp).append("|---> ");
}
public boolean contains(int[] value) {
validate(value);
return contains(root, value, 0);
}
public void insert(int[] value) {
validate(value);
root = insert(root, value, 0);
}
private void validate(int[] value) {
if (value.length != dimensions) {
throw new IllegalArgumentException("Length of the array [" + value.length + "] doesn't much dimension count of the tree [" + dimensions + ']');
}
}
private int toIdx(int depth) {
return depth % dimensions;
}
private boolean contains(KDNode node, int[] value, int depth) {
if (node == null) {
return false;
} else {
int idx = toIdx(depth);
if (node.value[idx] == value[idx] && Arrays.equals(node.value, value)) {
return true;
} else if (node.value[idx] >= value[idx]) {
return contains(node.left, value, depth + 1);
} else {
return contains(node.right, value, depth + 1);
}
}
}
private KDNode insert(KDNode node, int[] value, int depth) {
if (node == null) {
return new KDNode(value);
} else {
int idx = toIdx(depth);
if (node.value[idx] == value[idx] && Arrays.equals(node.value, value)) {
node.value = value;
} else if (node.value[idx] >= value[idx]) {
node.left = insert(node.left, value, depth + 1);
} else {
node.right = insert(node.right, value, depth + 1);
}
return node;
}
}
@Override
public String toString() {
String rootStr;
if (root == null) {
rootStr = "\t<empty>\n";
} else {
rootStr = "\tNode{key=0, values=" + Arrays.toString(root.value) + "}\n";
Set<Integer> last = new HashSet<>();
if (root.right == null) {
last.add(1);
}
rootStr += toString(root.left, 1, last);
last.add(1);
rootStr += toString(root.right, 1, last);
}
return "KDTree{\n" + rootStr + "}";
}
private String toString(KDNode node, int level, Set<Integer> last) {
if (node == null) {
return "";
}
StringBuilder curr = new StringBuilder("\t");
buildCatalogPrefix(curr, level, last);
curr.append("Node{key=")
.append(toIdx(level))
.append(", value=")
.append(Arrays.toString(node.value))
.append("}\n");
if (node.right == null) {
last.add(level + 1);
}
curr.append(toString(node.left, level + 1, last));
last.add(level + 1);
curr.append(toString(node.right, level + 1, last));
last.remove(level + 1);
return curr.toString();
}
private class KDNode {
private KDNode left, right;
private int[] value;
private KDNode(int[] value) {
this.value = value;
}
@Override
public String toString() {
return "KDNode{value=" + Arrays.toString(value) + '}';
}
}
}