438. Find All Anagrams in a String

Author: Partho Biswas

README.md

@@ -223,7 +223,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |14| [424. Longest Repeating Character Replacement](https://leetcode.com/problems/longest-repeating-character-replacement/)| [Python](https://tinyurl.com/wu6rdaw/424_Longest_Repeating_Character_Replacement.py)| **[Vid 1](https://tinyurl.com/svyns7x)**, [Vid 2](https://tinyurl.com/rj3yt25), [Art 1](https://tinyurl.com/yx34cd9c), [Art 2](https://tinyurl.com/suxeoj3), [Art 3](https://tinyurl.com/slpeqnd), [Art 4](https://tinyurl.com/sje2no8) | Medium | 📌 Sliding window, Very important |
 |15| **[76. Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/)** | [Python](https://tinyurl.com/wu6rdaw/76_Minimum_Window_Substring.py)| **[Vid 1](https://tinyurl.com/tv8lqpa)**, **[Vid 2](https://tinyurl.com/v38h4j4)**, **[Vid 3](https://tinyurl.com/ss5ue49)**  | Hard | 📌 Sliding window, Very important |
 |16| [727. Minimum Window Subsequence](https://leetcode.com/problems/minimum-window-subsequence/)| [Python](https://tinyurl.com/wu6rdaw/727_Minimum_Window_Subsequence.py)| [Vid 1](https://tinyurl.com/seyskk7), [Art 1](https://tinyurl.com/vs9qedt), [Art 2](https://tinyurl.com/v5tud73)  | Hard | 📌 Sliding window and DP, check the DP approach |
-|17| [438. Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string/)| [Python](https://tinyurl.com/wu6rdaw/438_Find_All_Anagrams_in_a_String.py)| **[Must](https://tinyurl.com/y8jsku3f)**, [Art 1](https://tinyurl.com/wzdp4yp) | Medium | 📌 Sliding window |
+|17| [438. Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string/)| [Python](https://tinyurl.com/wu6rdaw/438_Find_All_Anagrams_in_a_String.py), [Swift](https://tinyurl.com/wuja3c4/438_Find_All_Anagrams_in_a_String.swift) | **[Must](https://tinyurl.com/y8jsku3f)**, [Art 1](https://tinyurl.com/wzdp4yp) | Medium | 📌 Sliding window |
 |18| [567. Permutation in String](https://leetcode.com/problems/permutation-in-string/)| [Python](https://tinyurl.com/wu6rdaw/567_Permutation_in_String.py)| **[Must](https://tinyurl.com/y8jsku3f)** | Medium | 📌 Sliding window |
 |19| [844. Backspace String Compare](https://leetcode.com/problems/backspace-string-compare/)| [Python](https://tinyurl.com/wu6rdaw/844_Backspace_String_Compare.py)| --- | Easy | 📌 Two Pointer |
 |20| **[809. Expressive Words](https://tinyurl.com/vuv9uud)**| [Python](https://tinyurl.com/wu6rdaw/809_Expressive_Words.py)| [Art 1](https://tinyurl.com/rzlvfn7) | Medium | 📌 Logic ad analytical prolem |

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/438_Find_All_Anagrams_in_a_String.swift

@@ -0,0 +1,68 @@
+
+// Brute force approach | Time O(n^2) | TLE : 34 / 36 test cases passed.
+import Foundation
+class Solution {
+    func findAnagrams(_ s: String, _ p: String) -> [Int] {
+        var pMap = [Character:Int]()
+        for char in p {
+            pMap[char, default: 0] += 1
+        }
+        let sArr = Array(s)
+        var result = [Int]()
+        for start in 0..<sArr.count {
+            var need = pMap
+            for i in start..<sArr.count {
+                let curChar = sArr[i]
+                if var needVal = need[curChar], needVal > 0 {
+                    needVal -= 1
+                    if needVal == 0 {
+                        need.removeValue(forKey: curChar)
+                        if need.keys.count <= 0 {
+                            result.append(start)
+                            break
+                        }
+                    } else {
+                        need[curChar] = needVal
+                    }
+                } else {
+                    break
+                }
+            }
+        }
+        return result
+    }
+}
+
+// Sliding window | Time O(n)
+class Solution {
+    func findAnagrams(_ s: String, _ p: String) -> [Int] {
+        if s.count < p.count {
+            return []
+        }
+        let sArr = Array(s)
+        var result = [Int]()
+        var (pCounter, sCounter) = ([Character:Int](), [Character:Int]())
+        for char in p {
+            pCounter[char, default: 0] += 1
+        }
+        for i in 0..<(p.count - 1) {
+            sCounter[sArr[i], default: 0] += 1
+        }
+        
+        for right in (p.count - 1)..<sArr.count {
+            let rightChar = sArr[right]
+            sCounter[rightChar, default: 0] += 1
+            if sCounter == pCounter {
+                result.append(right - (p.count - 1))
+            }
+            let leftChar = sArr[right - (p.count - 1)]
+            if var prevVal = sCounter[leftChar] {
+                sCounter[leftChar] = prevVal - 1
+                if sCounter[leftChar] == 0 {
+                    sCounter.removeValue(forKey:leftChar)
+                }
+            }
+        }
+        return result
+    }
+}