From f904019d40e4e152f15920194bce3fff380d6ab6 Mon Sep 17 00:00:00 2001
From: szdytom <szdytom@163.com>
Date: Wed, 31 May 2023 15:37:47 +0800
Subject: [PATCH] add priority queue

---
 src/misc/priority_queue.js   | 51 ++++++++++++++++++++++++++++++++++++
 tests/priority_queue.test.js | 18 +++++++++++++
 2 files changed, 69 insertions(+)
 create mode 100644 src/misc/priority_queue.js
 create mode 100644 tests/priority_queue.test.js

diff --git a/src/misc/priority_queue.js b/src/misc/priority_queue.js
new file mode 100644
index 0000000..e8f7da0
--- /dev/null
+++ b/src/misc/priority_queue.js
@@ -0,0 +1,51 @@
+export class PriorityQueue {
+	constructor() {
+		this.val = [null];
+	}
+
+	push(value, priority) {
+		if (priority == null) {
+			priority = value;
+		}
+
+		this.val.push([value, priority]);
+		let id = this.val.length - 1;
+		while (id > 1 && this.val[id][1] > this.val[id >>> 1][1]) {
+			const kid = id >>> 1;
+			[this.val[id], this.val[kid]] = [this.val[kid], this.val[id]];
+			id = kid;
+		}
+		return this;
+	}
+
+	pop() {
+		let lv = this.val.pop();
+		if (this.val.length == 1) { return lv; }
+
+		let res = this.val[1];
+		this.val[1] = lv;
+		let id = 1;
+		while (id * 2 < this.val.length) {
+			if (this.val[id][1] > this.val[id * 2][1] && (id * 2 + 1 >= this.val.length || this.val[id][1] > this.val[id * 2 + 1][1])) {
+				break;
+			}
+
+			let kid = id * 2 + 1 >= this.val.length || this.val[id * 2][1] > this.val[id * 2 + 1][1] ? id * 2 : id * 2 + 1;
+			[this.val[id], this.val[kid]] = [this.val[kid], this.val[id]];
+			id = kid;
+		}
+		return res;
+	}
+
+	top() {
+		return this.val[1];
+	}
+
+	size() {
+		return this.val.length - 1;
+	}
+
+	empty() {
+		return this.size() == 0;
+	}
+}
\ No newline at end of file
diff --git a/tests/priority_queue.test.js b/tests/priority_queue.test.js
new file mode 100644
index 0000000..a65f07c
--- /dev/null
+++ b/tests/priority_queue.test.js
@@ -0,0 +1,18 @@
+import assert from 'node:assert';
+import { PriorityQueue } from '../src/misc/priority_queue.js';
+
+describe('PriorityQueue', function () {
+	it('everything', function() {
+		let q = new PriorityQueue();
+		q.push(1).push(2).push(-1).push('hi', 4);
+		assert.equal(q.size(), 4);
+		assert.equal(q.top()[0], 'hi');
+
+		assert.equal(q.pop()[0], 'hi');
+		assert.equal(q.pop()[0], 2);
+		assert.equal(q.pop()[0], 1);
+		assert.equal(q.pop()[0], -1);
+
+		assert.ok(q.empty());
+	});
+});
\ No newline at end of file