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183 lines (155 loc) · 4.34 KB
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package com.algorithm.playground.data.structure;
import java.util.*;
import static com.algorithm.playground.utils.CollectionUtils.list;
import static com.algorithm.playground.utils.CollectionUtils.sort;
import static java.util.Collections.max;
import static java.util.Comparator.comparingInt;
public class IntervalTree {
private Node root;
public IntervalTree() { }
public IntervalTree(Collection<Interval> intervals) {
if (!intervals.isEmpty()) {
List<Interval> leftSorted = sort(intervals, comparingInt(Interval::getLeft));
int min = leftSorted.get(0).left;
int max = max(intervals, comparingInt(Interval::getRight)).right;
root = buildNode(min, max, leftSorted);
}
}
public List<Interval> query(int left, int right) {
return query(left, right, root, new ArrayList<>());
}
public void insert(Interval interval) {
root = insert(root, interval);
}
public Node insert(Node node, Interval interval) {
if (node == null) {
int val = (interval.right - interval.left) / 2 + interval.left;
return new Node(val, list(interval));
} else {
if (interval.left <= node.value && interval.right >= node.value) {
node.insert(interval);
} else if (node.value > interval.right) {
node.left = insert(node.left, interval);
} else {
node.right = insert(node.right, interval);
}
}
return node;
}
private List<Interval> query(int left, int right, Node node, List<Interval> values) {
if (node != null) {
node.getIntervals(left, right, values);
int mid = node.value;
if (mid >= left && mid <= right) {
query(left, mid - 1, node.left, values);
query(mid + 1, right, node.right, values);
} else if (right < mid) {
query(left, mid - 1, node.left, values);
} else {
query(mid + 1, right, node.right, values);
}
}
return values;
}
private Node buildNode(int left, int right, List<Interval> leftSorted) {
if (leftSorted.isEmpty() || left > right) {
return null;
}
int mid = (right - left) / 2 + left;
List<Interval> intervals = new ArrayList<>();
List<Interval> leftValues = new ArrayList<>();
Iterator<Interval> iterator = leftSorted.iterator();
while (iterator.hasNext()) {
Interval curr = iterator.next();
if (curr.left > mid) {
break;
} else if (curr.right >= mid) {
intervals.add(curr);
iterator.remove();
} else {
leftValues.add(curr);
iterator.remove();
}
}
Node node = new Node(mid, intervals);
node.left = buildNode(left, mid - 1, leftValues);
node.right = buildNode(mid + 1, right, leftSorted);
return node;
}
@Override
public String toString() {
return "IntervalTree{" +
"root=" + root +
'}';
}
private static class Node {
private final int value;
private final List<Interval> leftSorted;
private Node left, right;
private Node(int value, List<Interval> leftSorted) {
this.value = value;
this.leftSorted = leftSorted;
}
private void getIntervals(int left, int right, List<Interval> intervals) {
for (Interval interval : leftSorted) {
if (interval.left > right) {
break;
} else if (interval.intersect(left, right)) {
intervals.add(interval);
}
}
}
public void insert(Interval interval) {
int idx = 0;
for (; idx < leftSorted.size(); idx++) {
if (leftSorted.get(idx).left > interval.left) {
break;
}
}
leftSorted.add(idx, interval);
}
@Override
public String toString() {
return "Node{" +
"value=" + value +
", leftSorted=" + leftSorted +
", left=" + left +
", right=" + right +
'}';
}
}
public static class Interval {
private final int left, right;
public Interval(int left, int right) {
this.left = left;
this.right = right;
}
public int getLeft() {
return left;
}
public int getRight() {
return right;
}
private boolean intersect(int li, int ri) {
return (left <= li && right >= li) || (ri >= left && right >= ri) || (li < left && ri > right);
}
@Override
public String toString() {
return "Interval{" +
"left=" + left +
", right=" + right +
'}';
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Interval interval = (Interval) o;
return left == interval.left && right == interval.right;
}
@Override
public int hashCode() {
return Objects.hash(left, right);
}
}
}