Solved leetcode array problems.

Author: jyotisirswa

DataStrucutureQuestions/Array/169. Majority Element.playground/Contents.swift

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+import UIKit
+
+//MARK: - https://leetcode.com/problems/majority-element/description/?envType=study-plan-v2&envId=top-interview-150
+/* Given an array nums of size n, return the majority element.
+ The majority element is the element that appears more than ⌊n / 2⌋ times. You may assume that the majority element always exists in the array.*/
+
+//Time: O(n) Space: O(1)
+
+func majorityElement(_ nums: [Int]) -> Int {
+    var majorityNumber = 0, count = 0
+    nums.forEach { num in
+        if count == 0 {
+            majorityNumber = num
+        }
+        count += num == majorityNumber ? 1 : -1
+    }
+    return majorityNumber
+}
+
+var nums = [2,2,1,1,1,2,2]
+print("Majority number is \(majorityElement(nums))")

DataStrucutureQuestions/Array/169. Majority Element.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

DataStrucutureQuestions/Array/26. Remove Duplicates from Sorted Array.playground/Contents.swift

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+import UIKit
+
+//MARK: - https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/?envType=study-plan-v2&envId=top-interview-150
+
+// - Complexity:
+   //   - time: O(n), where m is the number of elements in nums1, and n is the number of elements in nums2.
+   //   - space: O(1), only constant space is used.
+
+func removeDuplicates(_ nums: inout [Int]) -> Int {
+    if nums.count == 0 {
+        return 0
+    }
+    var i = 0
+    for j in 1..<nums.count {
+        guard nums[i] != nums[j] else { continue }
+        i += 1
+        nums[i] = nums[j]
+    }
+    return i + 1
+}
+
+
+
+var num1 = [1,1,1,2,2,3] // [0,0,1,1,1,2,2,3,3,4]
+print("Number of unique elements in array is \(removeDuplicates(&num1))")
+print(num1)

DataStrucutureQuestions/Array/26. Remove Duplicates from Sorted Array.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

DataStrucutureQuestions/Array/27. Remove Element.playground/Contents.swift

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+import UIKit
+
+//MARK: - https://leetcode.com/problems/remove-element/description/?envType=study-plan-v2&envId=top-interview-150
+// - Complexity:
+   //   - time: O(n), where m is the number of elements in nums1, and n is the number of elements in nums2.
+   //   - space: O(1), only constant space is used.
+
+func removeElement(_ nums: inout [Int], _ val: Int) -> Int {
+    guard nums.count > 0 else {
+        return 0
+    }
+    var i = nums.count - 1
+    while i >= 0 {
+        if nums[i] == val {
+            nums.remove(at : i)
+        }
+        i -= 1
+    }
+    return nums.count
+}
+var nums = [3,2,2,3]
+print(removeElement(&nums, 3))
+print(nums)

DataStrucutureQuestions/Array/27. Remove Element.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

DataStrucutureQuestions/Array/80. Remove Duplicates from Sorted Array II.playground/Contents.swift

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+import UIKit
+
+//MARK: - https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/description/?envType=study-plan-v2&envId=top-interview-150
+// - Complexity:
+   //   - time: O(n), where m is the number of elements in nums1, and n is the number of elements in nums2.
+   //   - space: O(1), only constant space is used.
+
+func removeDuplicates(_ nums: inout [Int]) -> Int {
+    let length =  nums.count
+    guard length > 2 else {
+        return length
+    }
+    var currentIndex = 1
+    for nextIndex in 2..<length where nums[currentIndex] != nums[currentIndex - 1] || nums[currentIndex] !=  nums[nextIndex]   {
+        currentIndex += 1
+        nums[currentIndex] = nums[nextIndex]
+    }
+    return currentIndex + 1
+}
+
+var num1 = [1,1,1,2,2,3]
+print("Number of elements in array after removing third common element is \(removeDuplicates(&num1))")

DataStrucutureQuestions/Array/80. Remove Duplicates from Sorted Array II.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

DataStrucutureQuestions/Array/88. Merge Sorted Array.playground/Contents.swift

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+import UIKit
+
+//MARK: - https://leetcode.com/problems/merge-sorted-array/description/?envType=study-plan-v2&envId=top-interview-150
+// - Complexity:
+   //   - time: O(m + n), where m is the number of elements in nums1, and n is the number of elements in nums2.
+   //   - space: O(1), only constant space is used.
+
+func merge(_ nums1: inout [Int], _ m: Int, _ nums2: [Int], _ n: Int) {
+    var m = m - 1
+    var n = n - 1
+    var last = m + n + 1
+    // Compare elements from the end of both arrays and insert the larger one at the end of nums1
+    while m >= 0 && n >= 0 {
+        if nums1[m] > nums2[n] {
+            nums1[last] = nums1[m]
+            m -= 1
+        } else {
+            nums1[last] = nums2[n]
+            n -= 1
+        }
+        last -= 1
+    }
+    
+    // If there are remaining elements in nums2, insert them in nums1
+    while n >= 0 {
+        nums1[last] = nums2[n]
+        last -= 1
+        n -= 1
+    }
+}
+
+var nums1 = [1,2,3,0,0,0]
+var nums2 = [2,5,6]
+print("nums1 before merging :- \(nums1)")
+print("---MERGING ELEMENTs---")
+merge(&nums1, 3, nums2, 3)
+nums1.remove(at: <#T##Int#>)
+print("nums1 after merging :- \(nums1)")
+
+

DataStrucutureQuestions/Array/88. Merge Sorted Array.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>