Create 1825-finding-mk-average.js

Author: everthis

1825-finding-mk-average.js

@@ -0,0 +1,109 @@
+/**
+ * @param {number} m
+ * @param {number} k
+ */
+const MKAverage = function (m, k) {
+  this.sum = 0
+  this.dataBuff = []
+  this.dataM = []
+  this.m = m
+  this.k = k
+  this.count = m - k - k
+}
+/**
+ * @param {number} num
+ * @return {void}
+ */
+MKAverage.prototype.addElement = function (num) {
+  const total = this.dataBuff.length
+  this.dataBuff.push(num)
+  if (total >= this.m) {
+    let index = binarySearch(
+      this.dataBuff,
+      this.dataM,
+      this.dataBuff[total - this.m]
+    )
+    this.dataM[index] = this.dataBuff.length - 1
+    if (index === 0 || num > this.dataBuff[this.dataM[index - 1]]) {
+      move2End(this.dataBuff, this.dataM, index)
+    } else if (
+      index === this.m - 1 ||
+      num < this.dataBuff[this.dataM[index - 1]]
+    ) {
+      move2Start(this.dataBuff, this.dataM, index)
+    }
+
+    this.sum = 0
+  } else {
+    this.dataM.push(this.dataBuff.length - 1)
+    move2Start(this.dataBuff, this.dataM, this.dataBuff.length - 1)
+  }
+}
+
+/**
+ * @return {number}
+ */
+MKAverage.prototype.calculateMKAverage = function () {
+  if (this.dataM.length < this.m) {
+    return -1
+  } else {
+    if (!this.sum) {
+      this.sum = calcSum(this.dataBuff, this.dataM, this.k, this.count)
+    }
+    return Math.floor(this.sum / this.count)
+  }
+}
+
+/**
+ * Your MKAverage object will be instantiated and called as such:
+ * var obj = new MKAverage(m, k)
+ * obj.addElement(num)
+ * var param_2 = obj.calculateMKAverage()
+ */
+function binarySearch(numArr, indexArr, tar) {
+  let left = 0
+  let right = indexArr.length - 1
+
+  while (left <= right) {
+    let mid = (left + right) >>> 1
+
+    if (numArr[indexArr[mid]] > tar) {
+      right = mid - 1
+    } else if (numArr[indexArr[mid]] < tar) {
+      left = mid + 1
+    } else {
+      return mid
+    }
+  }
+}
+function move2Start(numArr, indexArr, index) {
+  let tmp
+
+  while (index > 0 && numArr[indexArr[index]] < numArr[indexArr[index - 1]]) {
+    tmp = indexArr[index]
+    indexArr[index] = indexArr[index - 1]
+    indexArr[index - 1] = tmp
+    index--
+  }
+}
+function move2End(numArr, indexArr, index) {
+  let tmp
+
+  while (
+    index < indexArr.length - 1 &&
+    numArr[indexArr[index]] > numArr[indexArr[index + 1]]
+  ) {
+    tmp = indexArr[index]
+    indexArr[index] = indexArr[index + 1]
+    indexArr[index + 1] = tmp
+    index++
+  }
+}
+
+function calcSum(numArr, indexArr, start, count) {
+  let sum = 0
+  for (let i = 0; i < count; i++) {
+    sum += numArr[indexArr[i + start]]
+  }
+  return sum
+}