713.Subarray Product Less Than K
双指针
Given an array of integers nums
and an integer k
, return the number of contiguous subarrays where the product of all the elements in the subarray is strictly less than k
.
Example 1:
Input: nums = [10,5,2,6], k = 100
Output: 8
Explanation: The 8 subarrays that have product less than 100 are:
[10], [5], [2], [6], [10, 5], [5, 2], [2, 6], [5, 2, 6]
Note that [10, 5, 2] is not included as the product of 100 is not strictly less than k.
Example 2:
Input: nums = [1,2,3], k = 0
Output: 0
Constraints:
1 <= nums.length <= 3 * 104
1 <= nums[i] <= 1000
0 <= k <= 106
分析:双指针,让范围内积始终<k。
res+= right-left+1 这里是计算每次增加的subarray数量, 每增加一个right, 都计算新的end with right的subarray 数量
```python3
class Solution:
def numSubarrayProductLessThanK(self, nums: List[int], k: int) -> int:
if k <= 1:
return 0
left=0
n = len(nums)
product = 1
res = 0
for right in range(n):
product *= nums[right]
while product >= k:
product //= nums[left]
left += 1
res += right-left+1
return res
```
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