Merge pull request #33 from mohshin-shah/31-minimum-window-with-all-c…

…haracters-from-other-string

feat: Add `PermutationOfPatternInString` algorithm fixes #31

Sources/SlidingWindow/MinimumWindowMatchingPattern.swift

@@ -0,0 +1,76 @@
+//
+//  PermutationOfPatternInString.swift
+//
+//
+//  Created by Mohshinsha Shahmadar on 2024-09-09.
+//
+
+import Foundation
+/**
+ Problem Statement
+ Given a string and a pattern, find out if the string contains any permutation of the pattern.
+
+ Example 1:
+
+ Input: str="oidbcaf", pattern="abc"
+ Output: true
+ Explanation: The string contains "bca" which is a permutation of the given pattern.
+ Example 2:
+
+ Input: str="odicf", pattern="dc"
+ Output: false
+ Explanation: No permutation of the pattern is present in the given string as a substring.
+ Example 3:
+
+ Input: str="bcdxabcdy", pattern="bcdyabcdx"
+ Output: true
+ Explanation: Both the string and the pattern are a permutation of each other.
+ Example 4:
+
+ Input: str="aaacb", pattern="abc"
+ Output: true
+ Explanation: The string contains "acb" which is a permutation of the given pattern.
+ */
+func findPermutationOfPatternInString(
+  string: String,
+  pattern p: String
+) -> Bool {
+  var windowStart = 0
+  let array = Array(string)
+  let pattern = Array(p)
+
+  let patternMap: [Character: Int] = pattern.reduce(into: [:]) { map, char in
+    map[char, default: 0] += 1
+  }
+
+  var matchCount = 0
+  var windowMap = [Character: Int]()
+
+  for (windowEnd, char) in string.enumerated() {
+    windowMap.increment(char)
+
+    // Check if the frequency of the current character matches that in the patternMap
+    if let patternFreq = patternMap[char], patternFreq == windowMap[char] {
+      matchCount += 1
+    }
+
+    if windowEnd >= pattern.count {
+      let windowStartChar = array[windowStart]
+
+      if let pC = patternMap[windowStartChar],
+         let wC = windowMap[windowStartChar],
+         pC == wC {
+        matchCount -= 1
+      }
+
+      windowMap.decrement(windowStartChar)
+      windowStart += 1
+    }
+
+    if matchCount == patternMap.count {
+      return true
+    }
+  }
+
+  return false
+}

Tests/SwiftyAlgorithmsTests/SlidingWindow/MinimumWindowMatchingPatternTests.swift

@@ -0,0 +1,29 @@
+//
+//  PermutationOfPatternInStringTests.swift
+//
+//
+//  Created by Mohshinsha Shahmadar on 2024-09-09.
+//
+
+import Foundation
+import XCTest
+@testable import SwiftyAlgorithms
+
+final class PermutationOfPatternInStringTests: XCTestCase {
+  func testPermutationOfPatternInString() {
+
+    let testCases: [AlgorithmTestCase] = [
+      .init((string: "oidbcaf", pattern: "abc"), true),
+      .init((string: "odicf", pattern: "dc"), false),
+      .init((string: "bcdxabcdy", pattern: "bcdyabcdx"), true),
+      .init((string: "aaacb", pattern: "abc"), true),
+    ]
+
+    testAlgorithm(
+      name: "PermutationOfPatternInStringTests",
+      with: testCases
+    ) { input in
+      findPermutationOfPatternInString(string: input.string, pattern: input.pattern)
+    }
+  }
+}

Tests/SwiftyAlgorithmsTests/TestEngine/AlgorithTestCase.swift

@@ -9,7 +9,7 @@ import Foundation
 import XCTest
 
 /// Represents a generic test case for an algorithm with multiple inputs.
-struct AlgorithmTestCase<Input, Output: Comparable> {
+struct AlgorithmTestCase<Input, Output: Equatable> {
   let input: Input
   let expected: Output
   let description: String?
@@ -29,7 +29,7 @@ extension XCTestCase {
   ///   - algorithmName: A human-readable name for the algorithm being tested.
   ///   - testCases: A list of test cases containing inputs (as tuples or structs) and expected outputs.
   ///   - algorithm: A closure that runs the algorithm with the given input.
-  func testAlgorithm<Input, Output: Comparable>(
+  func testAlgorithm<Input, Output: Equatable>(
     name: String,
     with testCases: [AlgorithmTestCase<Input, Output>],
     algorithm: (Input) -> Output