leetcode_1207独一无二的出现次数

统计出现次数，判断是否重复

function uniqueOccurrences(arr: number[]): boolean {
 let result: Array<number> = []
 let length:number = 1
 arr.sort((a, b) => a-b)
 for(let i=1; i<arr.length; i++){
   if(arr[i]===arr[i-1]){
      length++
   } else {
     result.push(length)
     length = 1
   }
 }
 result.push(length)
 result.sort((a, b) => a-b)
 for(let j=1; j<result.length; j++){
     if(result[j]===result[j-1]){
         return false
     }
 }
 return true
};