[SeongA] WEEK 06 solutions

container-with-most-water/delight010.swift

@@ -0,0 +1,22 @@
+class Solution {
+    func maxArea(_ height: [Int]) -> Int {
+        var maxArea = 0
+        var startPointIndex = 0
+        var endPointIndex = height.count - 1
+        while startPointIndex < endPointIndex {
+            let minHeight = min(height[startPointIndex], height[endPointIndex])
+            let area = minHeight * (endPointIndex - startPointIndex)
+            maxArea = max(maxArea, area)
+            if height[startPointIndex] < height[endPointIndex] {
+                startPointIndex += 1
+            } else {
+                endPointIndex -= 1
+            }
+        }
+        return maxArea
+    }
+}
+
+// Time Complexity O(N)
+// Space Complexity O(1)
+

design-add-and-search-words-data-structure/delight010.swift

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+class WordDictionary {
+
+    class TrieNode {
+        var children: [Character: TrieNode] = [:]
+        var isEndOfWord: Bool = false
+    }
+
+    var root: TrieNode
+
+    init() {
+        root = TrieNode()
+    }
+
+    func addWord(_ word: String) {
+        var currentNode = root
+        for (index, char) in word.enumerated() {
+            if currentNode?.children[char] == nil {
+                currentNode?.children[char] = TrieNode()
+            }
+            currentNode = currentNode?.children[char]
+        }
+        currentNode?.isEndOfWord = true
+    }
+
+    func search(_ word: String) -> Bool {
+        return dfs(root, word: word, index: 0)
+    }
+
+    func dfs(_ node: TrieNode?, word: String, index: Int) -> Bool {
+        guard let currentNode = node else {
+            return false
+        }
+        if index == word.count {
+            return currentNode.isEndOfWord
+        }
+
+        let char = Array(word)[index]
+        if char == "." {
+            for child in currentNode.children.values {
+                let result = dfs(child, word: word, index: index + 1)
+                if result {
+                    return true
+                }
+            }
+        } else {
+            if let child = currentNode.children[char] {
+                return dfs(child, word: word, index: index + 1)
+            } else {
+                return false
+            }
+        }
+
+        return false
+    }
+}
+

longest-increasing-subsequence/delight010.swift

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+class Solution {
+    func lengthOfLIS(_ nums: [Int]) -> Int {
+        var tails: [Int] = []
+        for num in nums {
+            if let lastValue = tails.last {
+                if num > lastValue {
+                    tails.append(num)
+                } else {
+                    if let index = tails.firstIndex(where: { $0 >= num }) {
+                        tails[index] = num
+                    }
+                }
+            } else {
+                tails.append(num)
+            }
+        }
+
+        return tails.count
+    }
+}
+

spiral-matrix/delight010.swift

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+class Solution {
+    func spiralOrder(_ matrix: [[Int]]) -> [Int] {
+        var answer: [Int] = []
+        var top = 0
+        var bottom = matrix.endIndex - 1
+        var left = 0
+        var right = matrix[0].endIndex - 1
+        while top <= bottom && left <= right {
+            for column in left...right {
+                answer.append(matrix[top][column])
+            }
+            top += 1
+
+            if top <= bottom {
+                for row in top...bottom {
+                    answer.append(matrix[row][right])
+                }
+            }
+            right -= 1
+
+            if top <= bottom {
+                for column in stride(from: right, through: left, by: -1) {
+                    answer.append(matrix[bottom][column])
+                }
+            }
+            bottom -= 1
+
+            if left <= right {
+                for row in stride(from: bottom, through: top, by: -1) {
+                    answer.append(matrix[row][left])
+                }
+            }
+            left += 1
+        }
+        return answer
+    }
+}
+

valid-parentheses/delight010.swift

@@ -0,0 +1,19 @@
+class Solution {
+    func isValid(_ s: String) -> Bool {
+        let dictionary: [Character: Character] = [")":"(", "]":"[", "}":"{"]
+        var stack: [Character] = []
+        for char in s {
+            if let openBucket = dictionary[char] {
+                if stack.isEmpty == false, stack.removeLast() == openBucket {
+                    continue
+                } else {
+                    return false
+                }
+            }
+            stack.append(char)
+        }
+
+        return stack.isEmpty
+    }
+}
+