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=;

             int k=;

             int i=,j=-;

             for(int i=;i<aLen;i++){

                 if(A[i]>R){

                     k=i+;

                     j=i;

                 }else if(A[i]<L){

                     num+=(i-j)-(i-k+);

                 }else{

                     num+=(i-j);

                     k=i+;

                 }

             }

             return num;

     }

 };

巴特西

74th LeetCode Weekly Contest Number of Subarrays with Bounded Maximum

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