largest subarr sum 0

Author: sachuverma

Striver Sheet/Day-4/Largest subarray with 0 sum.cpp

@@ -0,0 +1,47 @@
+/*
+Largest subarray with 0 sum
+===========================
+
+Given an array having both positive and negative integers. The task is to compute the length of the largest subarray with sum 0.
+
+Example 1:
+Input:
+N = 8
+A[] = {15,-2,2,-8,1,7,10,23}
+Output: 5
+Explanation: The largest subarray with
+sum 0 will be -2 2 -8 1 7.
+Your Task:
+You just have to complete the function maxLen() which takes two arguments an array A and n, where n is the size of the array A and returns the length of the largest subarray with 0 sum.
+
+Expected Time Complexity: O(N*Log(N)).
+Expected Auxiliary Space: O(N).
+
+Constraints:
+1 <= N <= 104
+-1000 <= A[i] <= 1000, for each valid i
+*/
+
+int maxLen(int A[], int n)
+{
+  vector<int> prefix(n, 0);
+  prefix[0] = A[0];
+  for (int i = 1; i < n; ++i)
+    prefix[i] = prefix[i - 1] + A[i];
+
+  unordered_map<int, int> m;
+  int ans = 0;
+  for (int i = 0; i < n; ++i)
+  {
+    if (prefix[i] == 0)
+      ans = max(ans, i + 1);
+    if (m.find(prefix[i]) != m.end())
+    {
+      ans = max(ans, i - m[prefix[i]]);
+    }
+    else
+      m[prefix[i]] = i;
+  }
+
+  return ans;
+}

Striver Sheet/README.md

@@ -34,7 +34,7 @@
 - [Two Sum](https://leetcode.com/problems/two-sum/) - [Cpp Soultion](./Day-4/Two%20Sum.cpp)
 - [4Sum](https://leetcode.com/problems/4sum/) - [Cpp Soultion](./Day-4/4Sum.cpp)
 - [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/) - [Cpp Soultion](./Day-4/Longest%20Consecutive%20Sequence.cpp)
-- []() - [Cpp Soultion](./Day-4/.cpp)
+- [Largest subarray with 0 sum](https://practice.geeksforgeeks.org/problems/largest-subarray-with-0-sum/1#) - [Cpp Soultion](./Day-4/Largest%20subarray%20with%200%20sum.cpp)
 - []() - [Cpp Soultion](./Day-4/.cpp)
 - []() - [Cpp Soultion](./Day-4/.cpp)