create 0560-subarray-sum-equals-k.cs

Author: vikramsingh13

csharp/0560-subarray-sum-equals-k.cs

@@ -0,0 +1,37 @@
+public class Solution {
+    /// <summary>
+    /// Given an array of integers nums and an integer k, return the total number
+    /// of continuous subarrays whose sum equals to k.
+    /// </summary>
+    /// <param name="nums">The input array of integers.</param>
+    /// <param name="k">The target sum.</param>
+    /// <returns>The total number of subarrays with sum equal to k.</returns>
+    public int SubarraySum(int[] nums, int k) {
+        int result = 0;
+        int sum = 0;
+
+        // Create a dictionary to store the frequency of prefix sums
+        // The key is the prefix sum, and the value is the frequency
+        Dictionary<int, int> prefixSumFreq = new Dictionary<int, int>() { { 0, 1 }};
+
+        // Iterate through the array to calculate prefix sums and count subarrays
+        for (int i = 0; i < nums.Length; i++) {
+            sum += nums[i];
+
+            // If a prefix sum (sum - k) is present in the dictionary, it means there's a subarray with sum k
+            if (prefixSumFreq.ContainsKey(sum - k)) {
+                result += prefixSumFreq[sum - k];
+            }
+
+            // Update the prefix sum frequency dictionary
+            if (prefixSumFreq.ContainsKey(sum)) {
+                prefixSumFreq[sum]++;
+            }
+            else {
+                prefixSumFreq.Add(sum, 1);
+            }
+        }
+
+        return result;
+    }
+}