[Hyun] Week 6 Solution Explanation

container-with-most-water/WhiteHyun.swift

@@ -0,0 +1,30 @@
+//  
+//  11. Container With Most Water
+//  https://leetcode.com/problems/container-with-most-water/description/
+//  Dale-Study
+//  
+//  Created by WhiteHyun on 2024/06/08.
+//  
+
+class Solution {
+  func maxArea(_ height: [Int]) -> Int {
+    var totalArea = 0
+    var left = 0
+    var right = height.endIndex - 1
+
+    while left < right {
+      let area = (right - left) * min(height[left], height[right])
+      if area > totalArea {
+        totalArea = area
+      }
+
+      if height[left] < height[right] {
+        left += 1
+      } else {
+        right -= 1
+      }
+    }
+
+    return totalArea
+  }
+}

find-minimum-in-rotated-sorted-array/WhiteHyun.swift

@@ -0,0 +1,25 @@
+//  
+//  153. Find Minimum in Rotated Sorted Array
+//  https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/
+//  Dale-Study
+//  
+//  Created by WhiteHyun on 2024/06/09.
+//  
+
+class Solution {
+  func findMin(_ nums: [Int]) -> Int {
+    var left = 0
+    var right = nums.count - 1
+    while left < right {
+      let mid = (left + right) >> 1
+
+      if nums[mid] > nums[right] {
+        left = mid + 1
+      } else {
+        right = mid
+      }
+    }
+
+    return nums[left]
+  }
+}

longest-repeating-character-replacement/WhiteHyun.swift

@@ -0,0 +1,30 @@
+//  
+//  424. Longest Repeating Character Replacement
+//  https://leetcode.com/problems/longest-repeating-character-replacement/description/
+//  Dale-Study
+//  
+//  Created by WhiteHyun on 2024/06/08.
+//  
+
+final class Solution {
+  func characterReplacement(_ s: String, _ k: Int) -> Int {
+    var maxFrequency = 0
+    var i = 0
+    var counter: [Character: Int] = [:]
+    let array = Array(s)
+
+    for index in array.indices {
+      counter[array[index], default: 0] += 1
+      if maxFrequency < counter[array[index]]! {
+        maxFrequency = counter[array[index]]!
+      }
+
+      if index - i + 1 > maxFrequency + k {
+        counter[array[i]]! -= 1
+        i += 1
+      }
+    }
+
+    return array.count - i
+  }
+}

longest-substring-without-repeating-characters/WhiteHyun.swift

@@ -0,0 +1,40 @@
+//  
+//  3. Longest Substring Without Repeating Characters
+//  https://leetcode.com/problems/longest-substring-without-repeating-characters/description/
+//  Dale-Study
+//  
+//  Created by WhiteHyun on 2024/06/08.
+//  
+
+class Solution {
+  func lengthOfLongestSubstring(_ s: String) -> Int {
+    var longest: Int = .min
+    let array = Array(s)
+
+    var set: Set<Character> = []
+    var startIndex = 0
+    for index in array.indices {
+      if set.contains(array[index]) == false {
+        set.insert(array[index])
+        continue
+      }
+
+      if longest < index - startIndex {
+        longest = index - startIndex
+      }
+
+      while array[startIndex] != array[index] {
+        set.remove(array[startIndex])
+        startIndex += 1
+      }
+      startIndex += 1
+    }
+
+    if longest < array.endIndex - startIndex {
+      longest = array.endIndex - startIndex
+    }
+
+
+    return longest
+  }
+}

search-in-rotated-sorted-array/WhiteHyun.swift

@@ -0,0 +1,41 @@
+//  
+//  33. Search in Rotated Sorted Array
+//  https://leetcode.com/problems/search-in-rotated-sorted-array/description/
+//  Dale-Study
+//  
+//  Created by WhiteHyun on 2024/06/10.
+//  
+
+final class Solution {
+  func search(_ nums: [Int], _ target: Int) -> Int {
+    guard nums.count != 1
+    else {
+      return nums[0] == target ? 0 : -1
+    }
+
+    var left = 0
+    var right = nums.count - 1
+
+    while left <= right {
+      let mid = (left + right) >> 1
+
+      if nums[mid] == target { return mid }
+
+      if nums[left] <= nums[mid] {
+        if target > nums[mid] || target < nums[left] {
+          left = mid + 1
+        } else {
+          right = mid - 1
+        }
+      } else {
+        if target < nums[mid] || target > nums[right] {
+          right = mid - 1
+        } else {
+          left = mid + 1
+        }
+      }
+    }
+
+    return -1
+  }
+}