min priority queue.js

function MinPQ() {
  this.size = 0;
  this.data = Array.from({ length: 10 });
}
MinPQ.prototype.swap = function (i, j) {
  const tmp = this.data[i];
  this.data[i] = this.data[j];
  this.data[j] = tmp;
}
MinPQ.prototype.up = function (k) {
  while (k > 1 && this.data[Math.floor(k / 2)] > this.data[k]) {
    this.swap(Math.floor(k / 2), k);
    k = Math.floor(k / 2);
  }
}

MinPQ.prototype.down = function (k) {
  while (k <= this.size) {
    if (2 * k + 1 <= this.size) {
      // check both
      const leftV = this.data[2 * k]
      const rightV = this.data[2 * k + 1]
      const minIndex = leftV < rightV ? 2 * k : 2 * k + 1;
      const v = this.data[minIndex]
      if (v < this.data[k]) {
        this.swap(minIndex, k);
        k = minIndex
      } else {
        break;
      }
    } else if (2 * k <= this.size) {
      // check left
      const leftV = this.data[2 * k]
      if (leftV < this.data[k]) {
        this.swap(2 * k, k)
        k = 2 * k;
      } else {
        break;
      }
    } else {
      break;
    }
  }

}

MinPQ.prototype.grow = function (v) {
  const cap = this.data.length - 1;
  const oldData = this.data;
  const newCap = cap * 2 + 1;
  const data = Array.from({ length: newCap });
  for (let i = 1; i <= this.size; i++) {
    data[i] = oldData[i];
  }
  this.data = data;
}
MinPQ.prototype.getCap = function () {
  return this.data.length - 1;
}
MinPQ.prototype.insert = function (v) {
  
  while (this.size >= this.getCap()) {
    this.grow()
  }
  this.data[++this.size] = v;
  this.up(this.size);
}

MinPQ.prototype.remove = function () {
  if (this.size) {
    const v = this.data[1];
    this.data[1] = this.data[this.size--];
    this.down(1);
    return v;
  } else {
    return undefined;
  }
}

MinPQ.prototype.isEmpty = function () {
  return this.size === 0;
}