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#1852 - Distinct Numbers in Each Subarray
Problem Description
You are given an integer array nums of length n and an integer k. Your task is to find the number of distinct elements in every subarray of size k within nums.
Return an array ans such that ans[i] is the count of distinct elements in nums[i..(i + k - 1)] for each index 0 <= i < n - k.
Solution
/**
* @param {number[]} nums
* @param {number} k
* @return {number[]}
*/
var distinctNumbers = function(nums, k) {
const result = [];
const map = new Map();
for (let i = 0; i < k; i++) {
map.set(nums[i], (map.get(nums[i]) || 0) + 1);
}
result.push(map.size);
for (let i = k; i < nums.length; i++) {
const leftElement = nums[i - k];
const rightElement = nums[i];
map.set(leftElement, map.get(leftElement) - 1);
if (map.get(leftElement) === 0) {
map.delete(leftElement);
}
map.set(rightElement, (map.get(rightElement) || 0) + 1);
result.push(map.size);
}
return result;
};