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Offer-II-009 乘积小于 K 的子数组

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给定一个正整数数组nums和整数 k，请找出该数组内乘积小于k的连续的子数组的个数。
示例 1:
输入: nums = [10,5,2,6], k = 100
输出: 8
解释: 8 个乘积小于 100 的子数组分别为: [10], [5], [2], [6], [10,5], [5,2], [2,6], [5,2,6]。
需要注意的是 [10,5,2] 并不是乘积小于100的子数组。
示例 2:
输入: nums = [1,2,3], k = 0
输出: 0
提示:
1 <= nums.length <= 3 * 104
1 <= nums[i] <= 1000
0 <= k <= 106

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class Solution {
public:
    int numSubarrayProductLessThanK(vector<int>& nums, int k) {
        int left = 0;
        int right = 0;
        int product = 1;
        int len = nums.size();
        int cnt = 0;
        while(left <= right  && left < len)
        {
            product = product * nums[right];
            if(product < k)
            {
                cnt++;
                right++;
                if(right >= len){
                    left++;
                    right = left;
                    product = 1;
                }
            }
            else
            {
                left++;
                right = left;
                product = 1;
            }
        }
        return cnt;
    }
};

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class Solution {
public:
    int numSubarrayProductLessThanK(vector<int>& nums, int k) {
        int L=0, N=nums.size(), product=1, ans=0;
        for (int i = 0; i < N; ++i) 
        {
            product = product * nums[i];
            while (L <= i && product >=k ) product = product/nums[L++];
            ans += (i - L + 1);
        }
        return ans;
    }
};