Problem
Given an array of integers arr, return true **if the number of occurrences of each value in the array is *unique* or false otherwise**.
Example 1:
Input: arr = [1,2,2,1,1,3]
Output: true
Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.
Example 2:
Input: arr = [1,2]
Output: false
Example 3:
Input: arr = [-3,0,1,-3,1,1,1,-3,10,0]
Output: true
Constraints:
1 <= arr.length <= 1000-1000 <= arr[i] <= 1000
Solution
/**
* @param {number[]} arr
* @return {boolean}
*/
var uniqueOccurrences = function(arr) {
var numMap = {};
for (var i = 0; i < arr.length; i++) {
numMap[arr[i]] = (numMap[arr[i]] || 0) + 1;
}
var occureMap = {};
var nums = Object.keys(numMap);
for (var j = 0; j < nums.length; j++) {
if (occureMap[numMap[nums[j]]]) return false;
occureMap[numMap[nums[j]]] = true;
}
return true;
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).