[713] Subarray Product Less Than K

嗯，很好，我發現我還是不會sliding window！（大哭）

int numSubarrayProductLessThanK(int* nums, int numsSize, int k) {

int l=0, r=0;

int ret=0;

long long product=1;

if (k<=1)

return 0;

while (r< numsSize)

{

product *= nums[r++];

while (product>=k)

product /= nums[l++];

ret+= (r-l);

}

return ret;

}