63_countsubarrayswithfixedbounds.cpp

//https://leetcode.com/problems/count-subarrays-with-fixed-bounds/

class Solution {
public:
    long long countSubarrays(vector<int>& nums, int minK, int maxK) {
         // initialize some variables
        int n = nums.size();
        int leftBound = -1;
        int lastMin = -1, lastMax = -1;
        long long count = 0;
        
        for (int i = 0; i < n; i++) {
            // check if nums[i] is within the range [minK, maxK]
            if (nums[i] >= minK && nums[i] <= maxK) {
                // if nums[i] is equal to minK, update lastMin to the current index i
                lastMin = (nums[i] == minK) ? i : lastMin;
                // if nums[i] is equal to maxK, update lastMax to the current index i
                lastMax = (nums[i] == maxK) ? i : lastMax;
                // update the count by the number of valid subarrays between leftBound and the 
                // smaller of lastMin and lastMax
                count += max(0, min(lastMin, lastMax) - leftBound);
            } else {
                // if nums[i] is not within the range [minK, maxK], update leftBound to i
                leftBound = i;
                // reset lastMin and lastMax to -1
                lastMin = -1;
                lastMax = -1;
            }
        }
        
        // return the final count of valid subarrays
        return count;
    }
};