Today I have done leetcode's March LeetCoding Challenge with cpp.

March LeetCoding Challenge 29

Description

Count Subarrays Where Max Element Appears at Least K Times

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

Return the number of subarrays where the maximum element of nums appears at least k times in that subarray.

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

Example 1:

Input: nums = [1,3,2,3,3], k = 2
Output: 6
Explanation: The subarrays that contain the element 3 at least 2 times are: [1,3,2,3], [1,3,2,3,3], [3,2,3], [3,2,3,3], [2,3,3] and [3,3].

Example 2:

Input: nums = [1,4,2,1], k = 3
Output: 0
Explanation: No subarray contains the element 4 at least 3 times.

Constraints:

• 1 <= nums.length <= 105
• 1 <= nums[i] <= 106
• 1 <= k <= 105

Solution

class Solution {
public:
  long long countSubarrays(vector<int>& nums, int k) {
    long long answer = 0;
    int mmax = *max_element(nums.begin(), nums.end());

    int begin = 0;
    int end = 0;
    while(end < nums.size()) {
      if(nums[end] == mmax) {
        k -= 1;
      }
      end += 1;
      while(!k && begin < nums.size() && nums[begin++] != mmax) {}
      k += !k;
      answer += begin;
    }
    return answer;
  }
};