maximum length of sub-array

Author: aadityasinha-dotcom

Arrays/1D Arrays/maxLength_Of_Subarray.java

@@ -0,0 +1,41 @@
+
+import java.util.*;
+
+public class maxLength_Of_Subarray {
+    
+    public static void main(String[] args) {
+		Scanner sc = new Scanner(System.in);
+        int n = sc.nextInt();
+        int k = sc.nextInt();
+        int[] arr = new int[n];
+        for(int i = 0; i < n; i++){
+            arr[i] = sc.nextInt();
+        }
+        System.out.println(countSubarrays(arr,n,k));
+        sc.close();
+	}
+
+	public static int countSubarrays(int[] arr, int n, int k) {
+		
+		HashMap<Integer, Integer> map = new HashMap<>();  
+		int sum = 0, maxLen = 0;      // sum = prefix sum which stores sum of every element, maxlen = maximum length of sub array
+		for(int i = 0; i < n; i++){
+			sum += arr[i];
+			if(sum==k){
+				maxLen = i + 1;     // if k itself is present in the array then length will start from 0 to index of k 
+			}
+			if(!map.containsKey(sum)){     // putting frequencies of every sum
+				map.put(sum, i);
+			}
+			if(map.containsKey(sum-k)){
+				if(maxLen < (i-map.get(sum-k))){   // updating the maxlen variable from starting point of sub array to end point
+					maxLen = i - map.get(sum-k);
+				}
+			}
+		}
+		
+		return maxLen;
+			
+	}
+
+}