[LeetCode] 2958. Length of Longest Subarray With at Most K Frequency

You are given an integer array nums and an integer k.

The frequency of an element x is the number of times it occurs in an array.

An array is called good if the frequency of each element in this array is less than or equal to k.

Return the length of the longest good subarray of nums.

A subarray is a contiguous non-empty sequence of elements within an array.

Example 1:
Input: nums = [1,2,3,1,2,3,1,2], k = 2
Output: 6
Explanation: The longest possible good subarray is [1,2,3,1,2,3] since the values 1, 2, and 3 occur at most twice in this subarray. Note that the subarrays [2,3,1,2,3,1] and [3,1,2,3,1,2] are also good.
It can be shown that there are no good subarrays with length more than 6.

Example 2:
Input: nums = [1,2,1,2,1,2,1,2], k = 1
Output: 2
Explanation: The longest possible good subarray is [1,2] since the values 1 and 2 occur at most once in this subarray. Note that the subarray [2,1] is also good.
It can be shown that there are no good subarrays with length more than 2.

Example 3:
Input: nums = [5,5,5,5,5,5,5], k = 4
Output: 4
Explanation: The longest possible good subarray is [5,5,5,5] since the value 5 occurs 4 times in this subarray.
It can be shown that there are no good subarrays with length more than 4.

Constraints:
1 <= nums.length <= 105
1 <= nums[i] <= 109
1 <= k <= nums.length

最多 K 个重复元素的最长子数组。

给你一个整数数组 nums 和一个整数 k 。

一个元素 x 在数组中的 频率 指的是它在数组中的出现次数。

如果一个数组中所有元素的频率都 小于等于 k ,那么我们称这个数组是 好 数组。

请你返回 nums 中 最长好 子数组的长度。

子数组 指的是一个数组中一段连续非空的元素序列。

思路

思路不难想到是滑动窗口,还是用类似 76 题的模板解决这道题。

复杂度

时间O(n)
空间O(n)

代码

Java实现

class Solution {
public int maxSubarrayLength(int[] nums, int k) {
int n = nums.length;
int start = 0;
int end = 0;
int res = 0;
HashMap<Integer, Integer> map = new HashMap<>();
while (end < n) {
int num1 = nums[end];
map.put(num1, map.getOrDefault(num1, 0) + 1);
end++;
while (map.get(num1) > k) {
int num2 = nums[start];
map.put(num2, map.get(num2) - 1);
start++;
}
res = Math.max(res, end - start);
}
return res;
}
}
posted @   CNoodle  阅读(11)  评论(0编辑  收藏  举报
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