From 9ed419e44a8cbcd29370de8dd6dcf1c01f0e05f7 Mon Sep 17 00:00:00 2001
From: andy_lien <andy922200@gmail.com>
Date: Mon, 22 Apr 2024 18:15:04 +0800
Subject: [PATCH] feat: PQ - dequeue

---
 app-ch9-20.js | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/app-ch9-20.js b/app-ch9-20.js
index f8236a4..9692fee 100644
--- a/app-ch9-20.js
+++ b/app-ch9-20.js
@@ -33,11 +33,54 @@ class PriorityQueue {
             parentIndex = Math.floor((newIndex - 1) / 2);
         }
     }
+
+    dequeue(){
+        if (this.values.length === 0) return null;
+        if (this.values.length === 1) {
+            const removedNode = this.values.pop();
+            return removedNode;
+        }
+
+        [this.values[0], this.values[this.values.length - 1]] = [this.values[this.values.length - 1], this.values[0]];
+
+        const removedNode = this.values.pop();
+        this.maxHeapify(0)
+
+        return removedNode;
+    }
+
+    maxHeapify(i) {
+        let largestIndex = undefined;
+        let left = i * 2 + 1;
+        let right = i * 2 + 2;
+        const length = this.values.length;
+        
+        left <= length - 1 && this.values[left].priority > this.values[i].priority
+            ? largestIndex = left
+            : largestIndex = i;
+
+        if (right <= length - 1 && this.values[right].priority > this.values[largestIndex].priority) {
+            largestIndex = right;
+        }
+
+        if (largestIndex !== i) {
+            [this.values[i], this.values[largestIndex]] = [this.values[largestIndex], this.values[i]];
+            this.maxHeapify(largestIndex);
+        }
+    }
 }
 
 const pq1 = new PriorityQueue();
 pq1.enqueue('Eat breakfast', 5);
 pq1.enqueue('Learn Java', 2);
 pq1.enqueue('Learn JavaScript', 7);
+pq1.enqueue('Buy Textbooks', 8);
+pq1.enqueue('Watch Netflix', 12);
+pq1.enqueue('Pay Bills', 15);
+
+console.log(pq1)
 
-console.log(pq1)
\ No newline at end of file
+while(pq1.values.length >= 1){
+    const { value, priority } = pq1.dequeue();
+    console.log(value + ' - Priority: ' + priority);
+}
\ No newline at end of file