2022-11-30.md

题目

1207. Unique Number of Occurrences

Given an array of integers arr, return true if the number of occurrences of each value in the array is unique, or false otherwise.

思路

代码

var uniqueOccurrences = function(arr) {
  const num2count = {}
  for (let i = 0; i < arr.length; i++) {
    num2count[arr[i]] = (num2count[arr[i]] || 0) + 1
  }
  const count2num = {}
  for (const num in num2count) {
    if (num2count[num] in count2num) {
      return false
    }
    count2num[num2count[num]] = num
  }
  return true
};