-
Notifications
You must be signed in to change notification settings - Fork 1
/
SubarrayProductLessThanK.java
71 lines (61 loc) · 2.04 KB
/
SubarrayProductLessThanK.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
package com.leetcode;
public class SubarrayProductLessThanK {
//https://leetcode.com/problems/subarray-product-less-than-k/
class Solution {
// 10 5 2 6
//-- 10
//----- 10 5
// - 5
// --- 5 2
// ----- 5 2 6
/**
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.
**/
//O(N)
public int numSubarrayProductLessThanK(int[] nums, int k) {
if (k <= 1) return 0;//see note below
int n = nums.length;
int l = 0;
int r = 0;
int prod = 1;
int result =0;
while(l<=r && r<n){
prod = prod * nums[r];//increase
while(prod >= k ){//can add l<=r to cover case k=0 but we checked edge condition above
prod = prod / nums[l];//reduce product Note:Array of positive integers so no divide by zero
l++;
}
result = result + (r-l)+1;//r=l=0 is one solution
r++;
}
return result;
}
}
//Recursive approach
//O(N*N) - for array [1,1,1,1,1,1] k > 1 creates n branches or depth max n
class SolutionTLE {
int result;
public int numSubarrayProductLessThanK(int[] nums, int k) {
result = 0;
for(int i = 0 ; i < nums.length ; i++){
backtrack(nums,i,nums[i],k);
}
return result;
}
public void backtrack(int[] nums, int pos, int product, int k){
if(pos == nums.length) return;
if(product < k){
result++;
}else{
return;
}
if(pos < nums.length -1){
backtrack(nums,pos+1,product*nums[pos+1] , k);
}
}
}
}