0163-missing-ranges

0163-missing-ranges.playground/Contents.swift

@@ -0,0 +1,37 @@
+/// 163. Missing Ranges
+/// Given a sorted integer array nums, where the range of elements are in the inclusive range
+/// [lower, upper], return its missing ranges.
+///
+/// Example:
+/// Input: nums = [0, 1, 3, 50, 75], lower = 0 and upper = 99,
+/// Output: ["2", "4->49", "51->74", "76->99"]
+
+import XCTest
+
+/// Approach: Iteration
+func findMissingRanges(_ nums: [Int], _ lower: Int, _ upper: Int) -> [String] {
+    var numbers = [lower - 1]
+    numbers.append(contentsOf: nums)
+    numbers.append(upper + 1)
+    var result: [String] = []
+    for i in 0..<numbers.count - 1 {
+        let difference = numbers[i + 1] - numbers[i]
+        guard difference > 1 else { continue }
+        if difference == 2 {
+            result.append(String(numbers[i] + 1))
+        } else {
+            result.append(String(numbers[i] + 1) + "->" + String(numbers[i + 1] - 1))
+        }
+    }
+    return result
+}
+
+class Tests: XCTestCase {
+    func testExample() {
+        let nums = [0, 1, 3, 50, 75]
+        let expected = ["2", "4->49", "51->74", "76->99"]
+        XCTAssertEqual(findMissingRanges(nums, 0, 99), expected)
+    }
+}
+
+Tests.defaultTestSuite.run()

0163-missing-ranges.playground/contents.xcplayground

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+<?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

@@ -54,6 +54,7 @@ You can visit the pages below to search problems by company tags. Then come back
 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
 84 | [Largest Rectangle in Histogram](https://leetcode.com/problems/largest-rectangle-in-histogram/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0084-largest-rectangle-in-histogram.playground/Contents.swift) | Stack
+163 | [Missing Ranges](https://leetcode.com/problems/missing-ranges/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0163-missing-ranges.playground/Contents.swift) | BFS
 200 | [Number of Islands](https://leetcode.com/problems/number-of-islands/description/) | [Solution](https://github.com/zhubofei/LeetCode-Swift/blob/master/0200-number-of-islands.playground/Contents.swift) | BFS
 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