74th LeetCode Weekly Contest Number of Subarrays with Bounded Maximum

We are given an array A of positive integers, and two positive integers L and R (L <= R).

Return the number of (contiguous, non-empty) subarrays such that the value of the maximum array element in that subarray is at least Land at most R.

Example :
Input: 
A = [2, 1, 4, 3]
L = 2
R = 3
Output: 3
Explanation: There are three subarrays that meet the requirements: [2], [2, 1], [3].

Note:

• L, R  and A[i] will be an integer in the range [0, 10^9].
• The length of A will be in the range of [1, 50000].

有多少连续的子数组，必须存在[L,R]，但不能超过R

应该知道了，A[i]在L，R之间是num+=(i-j)，超过R需要记录j=i，但如何处理小于L的数字

因为必须存在[L,R]，单纯的小于L不能算，那么就拿一个k记录一下不在[L,R]的位置，然后(i-j)-(i-k+1)就好了

class Solution {
public:
    int numSubarrayBoundedMax(vector<int>& A, int L, int R) {
            int aLen=A.size();
            int num=0;
            int k=0;
            int i=0,j=-1;
            for(int i=0;i<aLen;i++){
                if(A[i]>R){
                    k=i+1;
                    j=i;
                }else if(A[i]<L){
                    num+=(i-j)-(i-k+1);
                }else{
                    num+=(i-j);
                    k=i+1;
                }
            }
            return num;
    }
};