"Competitive-coding-3 done"

Problem-1.java

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+
+// Time Complexity :O(n)
+// Space Complexity :O(n)
+// Did this code successfully run on Leetcode :yes
+// Any problem you faced while coding this : a little near creating hashset logic
+
+
+// Your code here along with comments explaining your approach
+// Use a HashSet (prev_visited_elem) to track numbers seen so far so you can instantly check if a matching pair exists.
+// For each number, compute x = num - k and y = num + k and check if either value was seen before — if yes, that forms a valid k-diff pair.
+// Store each pair in a set (output) to avoid duplicates, and return the number of unique pairs found.
+
+class Solution {
+    public int findPairs(int[] nums, int k) {
+        if (k < 0) return 0;
+
+        HashSet<Integer> prev_visited_elem = new HashSet<>();
+        HashSet<String> output = new HashSet<>();
+
+        for (int num : nums) {
+            int x = num - k;
+            int y = num + k;
+
+            if (prev_visited_elem.contains(x)) {
+                // store pair in normalized order (smaller first)
+                int a = x;
+                int b = num;
+                output.add(a + "," + b);
+            }
+
+            if (prev_visited_elem.contains(y)) {
+                int a = num;
+                int b = y;
+                output.add(a + "," + b);
+            }
+
+            prev_visited_elem.add(num);
+        }
+
+        return output.size();
+    }
+}

Problem-1.py

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+# Time Complexity :O(n)
+# Space Complexity :O(n)
+# Did this code successfully run on Leetcode :yes
+# Any problem you faced while coding this : a little near creating hashset logic
+
+
+# Your code here along with comments explaining your approach
+# Use a HashSet (prev_visited_elem) to track numbers seen so far so you can instantly check if a matching pair exists.
+# For each number, compute x = num - k and y = num + k and check if either value was seen before — if yes, that forms a valid k-diff pair.
+# Store each pair in a set (output) to avoid duplicates, and return the number of unique pairs found.
+
+class Solution:
+    def findPairs(self, nums: List[int], k: int) -> int:
+        if k < 0:
+            return 0
+        prev_visited_elem = set()
+        output = set()
+        for num in nums:
+            x = num - k
+            y = num + k
+            if x in prev_visited_elem:
+                output.add((x, num))
+            if y in prev_visited_elem:
+                output.add((num, y))
+            prev_visited_elem.add(num)
+        return len(output)

Problem-2.java

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+// Time Complexity : O(n^2)
+// Space Complexity :O(n^2)
+// Did this code successfully run on Leetcode :yes
+// Any problem you faced while coding this :no
+
+
+// Your code here along with comments explaining your approach
+// Start with the first two base rows of Pascal’s Triangle: [1] and [1, 1].
+// For each new row, compute inner values by adding two adjacent numbers from the previous row.
+// Append 1 at the start and end of each row to complete it, and repeat until all rows are built.
+
+class Solution {
+    public List<List<Integer>> generate(int numRows) {
+        if (numRows == 1) {
+            List<List<Integer>> result = new ArrayList<>();
+            result.add(Arrays.asList(1));
+            return result;
+        }
+
+        if (numRows == 2) {
+            List<List<Integer>> result = new ArrayList<>();
+            result.add(Arrays.asList(1));
+            result.add(Arrays.asList(1, 1));
+            return result;
+        }
+
+        List<List<Integer>> output = new ArrayList<>();
+        output.add(Arrays.asList(1));
+        output.add(Arrays.asList(1, 1));
+
+        for (int i = 2; i < numRows; i++) {
+            List<Integer> prev = output.get(output.size() - 1);
+            List<Integer> newRow = buildRow(prev, i);
+            output.add(newRow);
+        }
+
+        return output;
+    }
+
+    // Helper method similar to your Python res_row()
+    private List<Integer> buildRow(List<Integer> prev, int i) {
+        List<Integer> row = new ArrayList<>();
+        row.add(1);
+
+        for (int k = 1; k < i; k++) {
+            row.add(prev.get(k - 1) + prev.get(k));
+        }
+
+        row.add(1);
+        return row;
+    }
+}

Problem-2.py

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+# Time Complexity : O(n^2)
+# Space Complexity :O(n^2)
+# Did this code successfully run on Leetcode :yes
+# Any problem you faced while coding this :no
+
+
+# Your code here along with comments explaining your approach
+# Start with the first two base rows of Pascal’s Triangle: [1] and [1, 1].
+# For each new row, compute inner values by adding two adjacent numbers from the previous row.
+# Append 1 at the start and end of each row to complete it, and repeat until all rows are built.
+
+class Solution:
+    def generate(self, numRows: int) -> List[List[int]]:
+        if numRows == 1:
+            return [[1]]
+        if numRows == 2:
+            return [[1],[1,1]]
+        output = [[1],[1,1]]
+        def res_row(prev,i):
+            result = []
+            result.append(1)
+            for k in range(1,i):
+                result.append(prev[k-1]+prev[k])
+            result.append(1)
+            return result
+        for i in range(2,numRows):
+            prev= output[-1]
+            numrow_result = res_row(prev,i)
+            output.append(numrow_result)
+        return output
+
+