Create 1172-dinner-plate-stacks.js

Author: everthis

1172-dinner-plate-stacks.js

@@ -0,0 +1,144 @@
+/**
+ * @param {number} capacity
+ */
+const DinnerPlates = function (capacity) {
+  this.capacity = capacity
+  this.stacks = []
+  this.pq = new PriorityQueue()
+}
+
+/**
+ * @param {number} val
+ * @return {void}
+ */
+DinnerPlates.prototype.push = function (val) {
+  if (this.pq.isEmpty()) {
+    if (
+      this.stacks.length > 0 &&
+      this.stacks[this.stacks.length - 1].length < this.capacity
+    ) {
+      this.stacks[this.stacks.length - 1].push(val)
+    } else {
+      this.stacks.push([])
+      this.stacks[this.stacks.length - 1].push(val)
+    }
+  } else {
+    const num = this.pq.pop()
+    this.stacks[num].push(val)
+  }
+}
+
+/**
+ * @return {number}
+ */
+DinnerPlates.prototype.pop = function () {
+  while (
+    this.stacks.length > 0 &&
+    this.stacks[this.stacks.length - 1].length === 0
+  ) {
+    const len = this.stacks.length - 1
+    while (!this.pq.isEmpty() && this.pq.peek() >= len) {
+      this.pq.pop()
+    }
+    this.stacks.pop()
+  }
+  if (this.stacks.length === 0) {
+    return -1
+  } else {
+    return this.stacks[this.stacks.length - 1].pop()
+  }
+}
+
+/**
+ * @param {number} index
+ * @return {number}
+ */
+DinnerPlates.prototype.popAtStack = function (index) {
+  const st = this.stacks[index]
+
+  if (st && st.length > 0) {
+    this.pq.push(index)
+    return st.pop()
+  }
+
+  return -1
+}
+
+/**
+ * Your DinnerPlates object will be instantiated and called as such:
+ * var obj = new DinnerPlates(capacity)
+ * obj.push(val)
+ * var param_2 = obj.pop()
+ * var param_3 = obj.popAtStack(index)
+ */
+class PriorityQueue {
+  constructor(len, compare) {
+    this.compare = (a, b) => {
+      return a < b
+    }
+    this.last = 0
+    this.arr = []
+  }
+  push(val) {
+    this.last++
+    this.arr[this.last] = val
+    this.up(this.last)
+  }
+  pop() {
+    if (this.isEmpty()) {
+      return null
+    }
+    const res = this.arr[1]
+    this.swap(1, this.last)
+    this.last--
+    this.down(1)
+    return res
+  }
+  up(lo) {
+    while (lo > 1) {
+      const currEl = this.arr[lo]
+      const parent = Math.floor(lo / 2)
+      const parentEl = this.arr[parent]
+      if (this.compare(currEl, parentEl)) {
+        this.swap(lo, parent)
+      } else {
+        break
+      }
+      lo = parent
+    }
+  }
+  down(hi) {
+    while (hi * 2 <= this.last) {
+      const currEl = this.arr[hi]
+      let nextEl = this.arr[hi * 2]
+      let nextIndex = hi * 2
+      if (
+        hi * 2 + 1 <= this.last &&
+        this.compare(this.arr[hi * 2 + 1], nextEl)
+      ) {
+        nextIndex = hi * 2 + 1
+        nextEl = this.arr[nextIndex]
+      }
+      if (this.compare(nextEl, currEl)) {
+        this.swap(hi, nextIndex)
+      } else {
+        break
+      }
+      hi = nextIndex
+    }
+  }
+  swap(i, j) {
+    const temp = this.arr[i]
+    this.arr[i] = this.arr[j]
+    this.arr[j] = temp
+  }
+  peek() {
+    if (this.isEmpty()) {
+      return null
+    }
+    return this.arr[1]
+  }
+  isEmpty() {
+    return this.last < 1
+  }
+}