Subarray Product Less Than K (M)
题目
Your are given an array of positive integers nums
.
Count and print the number of (contiguous) subarrays where the product of all the elements in the subarray is 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.
Note:
0 < nums.length <= 50000
.
0 < nums[i] < 1000
.
0 <= k < 10^6
.
题意
找到所有的连续子数组,使其积小于指定值。
思路
遍历数组所有元素作为区间右端点;对于每个右端点,找到最左侧的元素,使构成的区间的积小于指定值;累加以右端点为终点的子区间的数量。
代码实现
Java
public int numSubarrayProductLessThanK(int[] nums, int k) {
int count = 0;
int left = 0, product = 1;
for (int right = 0; right < nums.length; right++) {
product *= nums[right];
while (product >= k && left <= right) {
product /= nums[left++];
}
count += right - left + 1;
}
return count;
}