Complete competitive-coding-3

PairsWithKDiff.swift

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+//
+//  PairsWithKDiff.swift
+//  DSA-Practice
+//
+//  Created by Paridhi Malviya on 4/5/26.
+//
+
+class PairsWithKDiff {
+
+    init() {
+
+    }
+
+    func findPairs(_ nums: [Int], _ k: Int) -> Int {
+        if (k < 0) {
+            return 0
+        }
+
+        var seen = Set<Int>()
+        //store the smaller element in result to avoid duplicates
+        var result = Set<Int>()
+        for num in nums {
+             if (seen.contains(num - k)) {
+                result.insert(num-k)
+             }
+             if (seen.contains(num + k)) {
+                result.insert(num)
+             }
+             seen.insert(num)
+        }
+        return result.count
+    }
+
+    func findPairsUsingMap(_ nums: [Int], _ k: Int) -> Int {
+        var map = [Int: Int]()
+
+        for num in nums {
+            map[num, default: 0] += 1
+        }
+        var count = 0
+        for (num, frequency) in map {
+            if (k == 0) {
+                if (map[num]! > 1) {
+                    count += 1
+                }
+            } else if (map[num + k] != nil) {
+                count += 1
+            }
+        }
+        return count
+    }
+
+}

PascalsTriangle.swift

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+//
+//  PascalsTriangle.swift
+//  DSA-Practice
+//
+//  Created by Paridhi Malviya on 4/5/26.
+//
+
+class PascalsTriangle {
+
+    init() {
+
+    }
+
+    func generate(_ numRows: Int) -> [[Int]] {
+        var output = [[Int]]()
+
+        for i in 0..<numRows {
+            if (i <= 1) {
+                var o = [Int]()
+                for _ in 0...i {
+                    o.append(1)
+                }
+                output.append(o)
+            } else {
+                var o = Array(repeating: -1, count: i + 1)
+                for k in 0...i  {
+                    if (k == 0 || k == i) {
+                        o[k] = 1
+                    } else {
+                        o[k] = output[i-1][k-1] + output[i-1][k]
+                    }
+                }
+                output.append(o)
+            }
+        }
+        return output
+    }
+}