0066-plus-one

0066-plus-one.playground/Contents.swift

@@ -0,0 +1,35 @@
+/// 66. Plus One
+/// Given a non-empty array of digits representing a non-negative integer, plus one to the integer.
+/// The digits are stored such that the most significant digit is at the head of the list, and each
+/// element in the array contain a single digit.
+/// You may assume the integer does not contain any leading zero, except the number 0 itself.
+
+import XCTest
+
+/// Approach: Math
+func plusOne(_ digits: [Int]) -> [Int] {
+    var digits = digits
+    var carry = 1
+    for i in stride(from: digits.count - 1, through: 0, by: -1) {
+        digits[i] += carry
+        if digits[i] > 9 {
+            digits[i] = digits[i] % 10
+            carry = 1
+        } else {
+            carry =  0
+        }
+    }
+    if carry == 1 {
+        digits.insert(1, at: 0)
+    }
+    return digits
+}
+
+class Tests: XCTestCase {
+    func testExample() {
+        let digits = [1, 2, 3]
+        XCTAssertEqual(plusOne(digits), [1, 2, 4])
+    }
+}
+
+Tests.defaultTestSuite.run()

0066-plus-one.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

@@ -52,6 +52,7 @@ 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
+66 | [Plus One](https://leetcode.com/problems/plus-one/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0066-plus-one.playground/Contents.swift) | Math
 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