|
| 1 | +--- |
| 2 | +id: split-array-with-same-average |
| 3 | +title: Split Array With Same Average |
| 4 | +sidebar_label: 0805 Split Array With Same Average |
| 5 | +tags: |
| 6 | +- Java |
| 7 | +- Math |
| 8 | +- Array |
| 9 | +- Binary Search |
| 10 | +- Dynamic Programming |
| 11 | +- Bitmask |
| 12 | +description: "This document provides a solution where we split an array into two non-empty subsets such that both subsets have the same average." |
| 13 | +--- |
| 14 | + |
| 15 | +## Problem |
| 16 | + |
| 17 | +You are given an integer array $nums$. |
| 18 | + |
| 19 | +You should move each element of $nums$ into one of the two arrays $A$ and $B$ such that $A$ and $B$ are non-empty, and $average(A) == average(B)$. |
| 20 | + |
| 21 | +Return $true$ if it is possible to achieve that and $false$ otherwise. |
| 22 | + |
| 23 | +**Note** that for an array $arr$, $average(arr)$ is the sum of all the elements of $arr$ over the length of $arr$. |
| 24 | + |
| 25 | +### Examples |
| 26 | + |
| 27 | +**Example 1:** |
| 28 | + |
| 29 | +``` |
| 30 | +Input: nums = [1,2,3,4,5,6,7,8] |
| 31 | +
|
| 32 | +Output: true |
| 33 | +
|
| 34 | +Explanation: We can split the array into [1,4,5,8] and [2,3,6,7], and both of them have an average of 4.5 . |
| 35 | +
|
| 36 | +``` |
| 37 | +**Example 2:** |
| 38 | + |
| 39 | +``` |
| 40 | +Input: nums = [3,1] |
| 41 | +
|
| 42 | +Output: false |
| 43 | +
|
| 44 | +``` |
| 45 | + |
| 46 | +### Constraints |
| 47 | + |
| 48 | +- $1 <= nums.length <= 30$ |
| 49 | +- $0 <= nums[i] <= 10^4$ |
| 50 | +--- |
| 51 | + |
| 52 | +## Approach |
| 53 | + |
| 54 | +To solve the problem, we need to understand the nature of the allowed moves: |
| 55 | + |
| 56 | +1. **Calculate Total Sum**: |
| 57 | + |
| 58 | + - First, calculate the total sum of the array. |
| 59 | + |
| 60 | +2. **Sort the Array**: |
| 61 | + |
| 62 | + - Sorting helps in pruning the search space. |
| 63 | + |
| 64 | +3. **Iterate Over Possible Sizes**: |
| 65 | + |
| 66 | + - Iterate over possible subset sizes from 1 to n/2. For each size, check if the corresponding subset sum can be an integer. |
| 67 | + |
| 68 | +4. **Check for Possible Partition**: |
| 69 | + |
| 70 | + - Use a recursive function with memoization to check if it’s possible to partition the array into subsets with the required sum and size. |
| 71 | + |
| 72 | +## Solution for Split Array With Same Average |
| 73 | + |
| 74 | +- The problem requires us to split an array into two non-empty subsets such that both subsets have the same average. |
| 75 | + |
| 76 | +- For two subsets to have the same average, the sum of elements in each subset divided by their respective lengths must be equal. |
| 77 | + |
| 78 | +#### Code in Java |
| 79 | + |
| 80 | +```java |
| 81 | +import java.util.Arrays; |
| 82 | + |
| 83 | +class Solution { |
| 84 | + public boolean splitArraySameAverage(int[] nums) { |
| 85 | + int n = nums.length; |
| 86 | + int totalSum = Arrays.stream(nums).sum(); |
| 87 | + |
| 88 | + Arrays.sort(nums); |
| 89 | + |
| 90 | + for (int size = 1; size <= n / 2; size++) { |
| 91 | + if (totalSum * size % n == 0) { |
| 92 | + int target = totalSum * size / n; |
| 93 | + if (canPartition(nums, size, target, 0)) { |
| 94 | + return true; |
| 95 | + } |
| 96 | + } |
| 97 | + } |
| 98 | + |
| 99 | + return false; |
| 100 | + } |
| 101 | + |
| 102 | + private boolean canPartition(int[] nums, int size, int target, int start) { |
| 103 | + if (size == 0) { |
| 104 | + return target == 0; |
| 105 | + } |
| 106 | + |
| 107 | + for (int i = start; i <= nums.length - size; i++) { |
| 108 | + if (i > start && nums[i] == nums[i - 1]) { |
| 109 | + continue; |
| 110 | + } |
| 111 | + |
| 112 | + if (nums[i] > target) { |
| 113 | + break; |
| 114 | + } |
| 115 | + |
| 116 | + if (canPartition(nums, size - 1, target - nums[i], i + 1)) { |
| 117 | + return true; |
| 118 | + } |
| 119 | + } |
| 120 | + |
| 121 | + return false; |
| 122 | + } |
| 123 | + |
| 124 | + public static void main(String[] args) { |
| 125 | + Solution sol = new Solution(); |
| 126 | + |
| 127 | + // Test cases |
| 128 | + int[] nums1 = {1, 2, 3, 4, 5, 6, 7, 8}; |
| 129 | + System.out.println(sol.splitArraySameAverage(nums1)); // Output: true |
| 130 | + |
| 131 | + int[] nums2 = {3, 1}; |
| 132 | + System.out.println(sol.splitArraySameAverage(nums2)); // Output: false |
| 133 | + } |
| 134 | +} |
| 135 | +``` |
| 136 | + |
| 137 | +### Complexity Analysis |
| 138 | + |
| 139 | +#### Time Complexity: $O(2^ n/2)$ |
| 140 | + |
| 141 | +> **Reason**: Time Complexity is $O(2^ n/2)$. Because Each half of the array can generate $O(2^ n/2)$ subsets. |
| 142 | +
|
| 143 | +#### Space Complexity: $O(2^ n/2)$ |
| 144 | + |
| 145 | +> **Reason**: The space complexity is $O(2^ n/2)$, Because it helps in Storing subset sums and sizes. |
| 146 | +
|
| 147 | +# References |
| 148 | + |
| 149 | +- **LeetCode Problem:** [Split Array With Same Average](https://leetcode.com/problems/split-array-with-same-average/description/) |
| 150 | +- **Solution Link:** [Split Array With Same Average Solution on LeetCode](https://leetcode.com/problems/split-array-with-same-average/solutions/) |
| 151 | +- **Authors LeetCode Profile:** [Vivek Vardhan](https://leetcode.com/u/vivekvardhan43862/) |
0 commit comments