[doitduri] WEEK 06 solutions

container-with-most-water/doitduri.swift

@@ -0,0 +1,22 @@
+class Solution {
+    func maxArea(_ height: [Int]) -> Int {
+        var start = 0
+        var end = height.count - 1
+        var result = 0
+
+        while start < end {
+            let width = end - start
+            let waters = width * (min(height[start], height[end]))
+
+            result = max(result, waters)
+
+            if height[start] > height[end] {
+                end  = end - 1
+            } else {
+                start = start + 1
+            }
+        }
+
+        return result
+    }
+}

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

@@ -0,0 +1,57 @@
+class WordDictionary {
+    class TrieNode {
+        var children: [Character: TrieNode] = [:]
+        var isEndOfWord: Bool = false
+    }
+
+    private let root: TrieNode
+
+    init() {
+        root = TrieNode()
+    }
+
+    func addWord(_ word: String) {
+        let key = word.lowercased()
+        var current = root
+
+        for char in key {
+            if current.children[char] == nil {
+                current.children[char] = TrieNode()
+            }
+
+            if let node = current.children[char] {
+                current = node
+            }
+        }
+
+        current.isEndOfWord = true
+    }
+
+    func search(_ word: String) -> Bool {
+        let key = word.lowercased()
+        return searchInNode(Array(key), 0, root)
+    }
+
+    private func searchInNode(_ word: [Character], _ index: Int, _ node: TrieNode) -> Bool {
+        if index == word.count {
+            return node.isEndOfWord
+        }
+
+        let currentChar = word[index]
+
+        if currentChar == "." {
+            for (_, childNode) in node.children {
+                if searchInNode(word, index + 1, childNode) {
+                    return true
+                }
+            }
+            return false
+        } else {
+            guard let nextNode = node.children[currentChar] else {
+                return false
+            }
+
+            return searchInNode(word, index + 1, nextNode)
+        }
+    }
+}

valid-parentheses/doitduri.swift

@@ -0,0 +1,23 @@
+class Solution {
+    func isValid(_ s: String) -> Bool {
+        let pair: [Character: Character] = [
+            "(": ")",
+            "[": "]",
+            "{": "}"
+        ]
+
+        var stack: [Character] = []
+
+        for char in s {
+            if pair.keys.contains(char) {
+                stack.append(char)
+            } else {
+                if stack.isEmpty || pair[stack.removeLast()] != char {
+                    return false
+                }
+            }
+        }
+
+        return stack.isEmpty
+    }
+}