Two-Hundred-Forty-Seven Commit: Add Maximum Size Subarray Sum Equals k problem to Prefix Sum Section

Author: AAdewunmi

src/Prefix_Sum/Problem_Left_And_Right_Sum_Differences.java renamed to src/Prefix_Sum/Problem_2_Left_And_Right_Sum_Differences.java

@@ -3,7 +3,7 @@
 // Problem Statement: Left and Right Sum Differences (easy)
 // LeetCode Question: 2574. Left and Right Sum Differences
 
-public class Problem_Left_And_Right_Sum_Differences {
+public class Problem_2_Left_And_Right_Sum_Differences {
    public int[] findDifferenceArray(int[] nums){
        int n = nums.length;
        int[] leftSum = new int[n];

src/Prefix_Sum/Problem_3_Maximum_Size_SubArray_Sum_Equals_K.java

@@ -0,0 +1,28 @@
+package Prefix_Sum;
+
+// Problem Statement: Maximum Size Subarray Sum Equals k (medium)
+// LeetCode Question: 325. Maximum Size Subarray Sum Equals k
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Problem_3_Maximum_Size_SubArray_Sum_Equals_K {
+    public int maxSubArrayLen(int[] nums, int k){
+        Map<Integer, Integer> cumMap = new HashMap<>();
+        int cumSum = 0;
+        int maxLen = 0;
+        for (int i = 0; i < nums.length; i++) {
+            cumSum += nums[i];
+            if (cumSum == k) {
+                maxLen = i + 1;
+            }
+            if (cumMap.containsKey(cumSum - k)) {
+                maxLen = Math.max(maxLen, i - cumMap.get(cumSum - k));
+            }
+            if (!cumMap.containsKey(cumSum)) {
+                cumMap.put(cumSum, i);
+            }
+        }
+        return maxLen;
+    }
+}