qilingit
diff --git a/‎June-LeetCoding-Challenge/02-Delete-Node-In-A-Linked-List/Delete-Node-in-a-Linked-List.cs
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+6Lines changed: 6 additions & 0 deletions b/‎June-LeetCoding-Challenge/02-Delete-Node-In-A-Linked-List/Delete-Node-in-a-Linked-List.cs
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+6Lines changed: 6 additions & 0 deletions
diff --git a/‎June-LeetCoding-Challenge/05-Random-Pick-With-Weight/Random-Pick-With-Weight.cs
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+80Lines changed: 80 additions & 0 deletions b/‎June-LeetCoding-Challenge/05-Random-Pick-With-Weight/Random-Pick-With-Weight.cs
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+80Lines changed: 80 additions & 0 deletions
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+public class Solution {
+    public void DeleteNode(ListNode node) {
+        node.val = node.next.val;
+        node.next = node.next.next;
+        }
+}
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+// Solution: Binary search 
+// Runtime: 208 ms, faster than 95.23% of C# online submissions for Random Pick with Weight.
+// Memory Usage: 47.2 MB, less than 5.10% of C# online submissions for Random Pick with Weight.
+public class Solution
+{
+    private int sum = 0; //sum of all integers of array w
+    private int[] arr; //new Array, its index means index, its value means weight
+    private Random random = new Random();
+    public Solution(int[] w)
+    {
+        arr = new int[w.Length];
+        for (var i = 0; i < w.Length; i++)
+        {
+            sum += w[i];
+            arr[i] = sum;
+        }
+    }
+
+    //Binary search
+    public int PickIndex()
+    {
+        //Generate a random value between 0 and sum
+        var randomValue = random.Next(0, sum) + 1;
+        int left = 0, right = arr.Length - 1;
+        while (left <= right)
+        {
+            int mid = left + (right - left) / 2;
+            if (arr[mid] == randomValue)
+                return mid;
+            else if (arr[mid] > randomValue)
+                right = mid - 1;
+            else
+                left = mid + 1;
+        }
+
+        return left;
+    }
+}
+
+
+// Solution: Linear search 
+// Runtime: 400 ms, faster than 37.10% of C# online submissions for Random Pick with Weight.
+// Memory Usage: 47 MB, less than 5.10% of C# online submissions for Random Pick with Weight.
+public class Solution
+{
+    private int sum = 0; //sum of all integers of array w
+    private int[] arr; //new Array, its index means index, its value means weight
+    private Random random = new Random();
+    public Solution(int[] w)
+    {
+        arr = new int[w.Length];
+        for (var i = 0; i < w.Length; i++)
+        {
+            sum += w[i];
+            arr[i] = sum;
+        }
+    }
+
+    //Linear search
+    public int PickIndex()
+    {
+        //Generate a random value between 0 and sum
+        var randomeValue = random.Next(0, sum);
+
+        for (int i = 0; i < arr.Length; i++)
+        {
+            if (randomeValue < arr[i])
+            {
+                return i;
+            }
+        }
+        return 0;
+    }
+}
+
+/**
+ * Your Solution object will be instantiated and called as such:
+ * Solution obj = new Solution(w);
+ * int param_1 = obj.PickIndex();
+ */