Create 1244-design-a-leaderboard.js

Author: everthis

1244-design-a-leaderboard.js

@@ -0,0 +1,120 @@
+
+const Leaderboard = function() {
+  this.hash = {}
+};
+
+/** 
+ * @param {number} playerId 
+ * @param {number} score
+ * @return {void}
+ */
+Leaderboard.prototype.addScore = function(playerId, score) {
+  if(this.hash[playerId] == null) this.hash[playerId] = 0
+  this.hash[playerId] += score
+};
+
+/** 
+ * @param {number} K
+ * @return {number}
+ */
+Leaderboard.prototype.top = function(K) {
+  const pq = new PriorityQueue((a, b) => a < b)
+  const values = Object.values(this.hash)
+  // console.log(values)
+  for(const v of values) {
+    pq.push(v)
+    if(pq.size() > K) pq.pop()
+  }
+  // console.log(pq.heap)
+  let sum = 0
+  while(!pq.isEmpty()) {
+    sum += pq.pop()
+    
+  }
+  
+  return sum
+};
+
+/** 
+ * @param {number} playerId
+ * @return {void}
+ */
+Leaderboard.prototype.reset = function(playerId) {
+  delete this.hash[playerId]
+};
+
+/** 
+ * Your Leaderboard object will be instantiated and called as such:
+ * var obj = new Leaderboard()
+ * obj.addScore(playerId,score)
+ * var param_2 = obj.top(K)
+ * obj.reset(playerId)
+ */
+
+class PriorityQueue {
+  constructor(comparator = (a, b) => a > b) {
+    this.heap = []
+    this.top = 0
+    this.comparator = comparator
+  }
+  size() {
+    return this.heap.length
+  }
+  isEmpty() {
+    return this.size() === 0
+  }
+  peek() {
+    return this.heap[this.top]
+  }
+  push(...values) {
+    values.forEach((value) => {
+      this.heap.push(value)
+      this.siftUp()
+    })
+    return this.size()
+  }
+  pop() {
+    const poppedValue = this.peek()
+    const bottom = this.size() - 1
+    if (bottom > this.top) {
+      this.swap(this.top, bottom)
+    }
+    this.heap.pop()
+    this.siftDown()
+    return poppedValue
+  }
+  replace(value) {
+    const replacedValue = this.peek()
+    this.heap[this.top] = value
+    this.siftDown()
+    return replacedValue
+  }
+
+  parent = (i) => ((i + 1) >>> 1) - 1
+  left = (i) => (i << 1) + 1
+  right = (i) => (i + 1) << 1
+  greater = (i, j) => this.comparator(this.heap[i], this.heap[j])
+  swap = (i, j) => ([this.heap[i], this.heap[j]] = [this.heap[j], this.heap[i]])
+  siftUp = () => {
+    let node = this.size() - 1
+    while (node > this.top && this.greater(node, this.parent(node))) {
+      this.swap(node, this.parent(node))
+      node = this.parent(node)
+    }
+  }
+  siftDown = () => {
+    let node = this.top
+    while (
+      (this.left(node) < this.size() && this.greater(this.left(node), node)) ||
+      (this.right(node) < this.size() && this.greater(this.right(node), node))
+    ) {
+      let maxChild =
+        this.right(node) < this.size() &&
+        this.greater(this.right(node), this.left(node))
+          ? this.right(node)
+          : this.left(node)
+      this.swap(node, maxChild)
+      node = maxChild
+    }
+  }
+}