From 36231bb1ac6b113f515e5b51d96aca34f389be25 Mon Sep 17 00:00:00 2001
From: sneha-tambade <sneha.tambade06@gmail.com>
Date: Mon, 12 Jan 2026 18:23:59 -0800
Subject: [PATCH] Mock test problems solved

---
 KDiffPairsInAnArray.cs | 46 ++++++++++++++++++++++++++++++++++++++++++
 PascalsTriangle.cs     | 31 ++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)
 create mode 100644 KDiffPairsInAnArray.cs
 create mode 100644 PascalsTriangle.cs

diff --git a/KDiffPairsInAnArray.cs b/KDiffPairsInAnArray.cs
new file mode 100644
index 00000000..6689fee4
--- /dev/null
+++ b/KDiffPairsInAnArray.cs
@@ -0,0 +1,46 @@
+//Time Complexity : O(n)
+//Space Complexity : O(n)
+
+//Approach
+// Maintain Dictionary with keys and elements from the array , values as frequency
+// Iterate over keys and check sum = Key + K ,if dictionary contains that sum then count it as one pair 
+// If K is 0 then make sure frequency is greater than 1 then count.
+public class Solution
+{
+    public int FindPairs(int[] nums, int k)
+    {
+        int count = 0;
+        Dictionary<int, int> pair = new();
+        for (int i = 0; i < nums.Length; i++)
+        {
+            if (!pair.ContainsKey(nums[i]))
+            {
+                pair.TryAdd(nums[i], 1);
+            }
+            else
+            {
+                pair[nums[i]]++;
+            }
+        }
+        foreach (var key in pair.Keys)
+        {
+            int sum = key + k;
+            if (k == 0)
+            {
+                int val = pair[key];
+                if (val > 1)
+                {
+                    count++;
+                }
+
+            }
+            else if (pair.ContainsKey(sum))
+            {
+                count++;
+            }
+        }
+        return count;
+    }
+}
+
+
diff --git a/PascalsTriangle.cs b/PascalsTriangle.cs
new file mode 100644
index 00000000..6952209b
--- /dev/null
+++ b/PascalsTriangle.cs
@@ -0,0 +1,31 @@
+//Time Complexity : O(n^2)
+//Space Complexity : O(n^2)
+
+//Approach
+// Start with the first row [1] and add it to the result.
+// For each new row, set the first and last elements to 1.
+// Fill middle elements using prevRow[j−1] + prevRow[j], then add the row to the result.
+
+public class Solution
+{
+    public IList<IList<int>> Generate(int numRows)
+    {
+        List<IList<int>> result = new List<IList<int>>();
+        if (numRows == 0)
+            return result;
+        result.Add(new List<int>() { 1 });
+        for (int i = 1; i < numRows; i++)
+        {
+            List<int> list = new List<int>();
+            List<int> prevRow = (List<int>)result[i - 1];
+            list.Add(1);
+            for (int j = 1; j < prevRow.Count; j++)
+            {
+                list.Add(prevRow[j - 1] + prevRow[j]);
+            }
+            list.Add(1);
+            result.Add(list);
+        }
+        return result;
+    }
+}