# Find the length of the largest subarray with 0 sum | GeeksForGeeks

Subscribe to my newsletter and never miss my upcoming articles

Given an array of integers, find the length of the longest sub-array with sum equals to 0.

Examples :

Input: arr[] = {15, -2, 2, -8, 1, 7, 10, 23}; Output: 5 Explanation: The longest sub-array with elements summing up-to 0 is {-2, 2, -8, 1, 7}

Input: arr[] = {1, 2, 3} Output: 0 Explanation:There is no subarray with 0 sum

Input: arr[] = {1, 0, 3} Output: 1 Explanation: The longest sub-array with elements summing up-to 0 is {0}

``````Approach: Prefix Sum

// A Java program to find maximum length subarray with 0 sum

class MaxLenZeroSumSub {

// Returns length of the maximum length subarray with 0 sum
static int maxLen(int arr[])
{
// Creates an empty hashMap hM
HashMap<Integer, Integer> hM = new HashMap<Integer, Integer>();

int sum = 0; // Initialize sum of elements
int max_len = 0; // Initialize result

// Traverse through the given array
for (int i = 0; i < arr.length; i++) {
// Add current element to sum
sum += arr[i];

if (arr[i] == 0 && max_len == 0)
max_len = 1;

if (sum == 0)
max_len = i + 1;

// Look this sum in hash table
Integer prev_i = hM.get(sum);

// If this sum is seen before, then update max_len
// if required
if (prev_i != null)
max_len = Math.max(max_len, i - prev_i);
else // Else put this sum in hash table
hM.put(sum, i);
}

return max_len;
}

// Drive method
public static void main(String arg[])
{
int arr[] = { 15, -2, 2, -8, 1, 7, 10, 23 };
System.out.println("Length of the longest 0 sum subarray is "
+ maxLen(arr));
}
}
``````