0482-license-key-formatting

0482-license-key-formatting.playground/Contents.swift

@@ -0,0 +1,36 @@
+/// 482. License Key Formatting
+/// You are given a license key represented as a string S which consists only alphanumeric
+/// character and dashes. The string is separated into N+1 groups by N dashes.
+/// Given a number K, we would want to reformat the strings such that each group contains exactly
+/// K characters, except for the first group which could be shorter than K, but still must contain
+/// at least one character. Furthermore, there must be a dash inserted between two groups and all
+/// lowercase letters should be converted to uppercase.
+/// Given a non-empty string S and a number K, format the string according to the rules
+/// described above.
+
+import XCTest
+
+/// Approach: String
+func licenseKeyFormatting(_ s: String, _ k: Int) -> String {
+    var s = Array(s.uppercased())
+    var result: [Character] = []
+    for i in stride(from: s.count - 1, through: 0, by: -1) {
+        guard s[i] != "-" else { continue }
+        if result.count % (k + 1) == k {
+            result.append("-")
+        }
+        result.append(s[i])
+    }
+    return String(result.reversed())
+}
+
+
+class Tests: XCTestCase {
+    func testExample() {
+        let s = "5F3Z-2e-9-w"
+        let k = 4
+        XCTAssertEqual(licenseKeyFormatting(s, k), "5F3Z-2E9W")
+    }
+}
+
+Tests.defaultTestSuite.run()

0482-license-key-formatting.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

README.md

@@ -52,5 +52,6 @@ You can visit the pages below to search problems by company tags. Then come back
 31 | [Next Permutation](https://leetcode.com/problems/next-permutation/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0031-next-permutation.playground/Contents.swift) | Two Pointers
 32 | [Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0032-longest-valid-parentheses.playground/Contents.swift) | Stack
 33 | [Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0033-search-in-rotated-sorted-array.playground/Contents.swift) | Binary Search
+482 | [License Key Formatting](https://leetcode.com/problems/license-key-formatting/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0482-license-key-formatting.playground/Contents.swift) | String
 681 | [Next Closest Time](https://leetcode.com/problems/next-closest-time/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0681-next-closest-time.playground/Contents.swift) | Simulation
 683 | [K Empty Slots](https://leetcode.com/problems/k-empty-slots/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0683-k-empty-slots.playground/Contents.swift) | Sliding Window