add interview-3 solutions

W3_interview_k-diff-pairs.py

@@ -0,0 +1,24 @@
+class Solution:
+    def findPairs(self, nums: List[int], k: int) -> int:
+
+        seen = set()
+        result = set()
+
+        for i in range(0, len(nums)):
+            big = nums[i] + k
+            small = nums[i] - k
+
+            if big in seen:
+                res = tuple(sorted([nums[i], big]))
+                result.add(res)
+
+            if small in seen:
+                res1 = tuple(sorted([nums[i], small]))
+                result.add(res1)
+
+            seen.add(nums[i])
+
+        return len(result)
+
+# Time complexity: O(n)
+# Space complexity: O(n)

W3_interview_pascals.py

@@ -0,0 +1,26 @@
+class Solution:
+    def generate(self, numRows: int) -> List[List[int]]:
+
+        result = []
+
+        # Insert 0s for all the rows in in creasing order
+        for i in range(numRows):
+            row = [0] * (i + 1)
+            result.append(row)
+
+        # Insert 1s in first and last index of each row
+        for i in range(numRows):
+            result[i][0] = 1
+            result[i][-1] = 1
+
+        # Fill the middle values
+        for i in range(2, numRows):
+            for j in range(1, i):
+                result[i][j] = result[i - 1][j - 1] + result[i - 1][j]
+
+        return result
+
+# Time complexity: O(numRows^2)
+# Space complexity: O(numRows^2), because we store the full triangle
+
+