Part of Leetcode top 150 interview questions

Author: jyotisirswa

DataStrucutureQuestions/Array/11. Container With Most Water.playground/Contents.swift

@@ -0,0 +1,30 @@
+import UIKit
+
+func maxArea(_ height: [Int]) -> Int {
+    var left = 0, right = height.count - 1, maxLeft = height[left], maxRight = height[right], waterFilled = 0, maxDifference = 0
+    while left < right {
+         maxLeft = height[left]
+         maxRight = height[right]
+        if maxLeft < maxRight {
+           if (maxLeft * maxRight) - (right - left) >  waterFilled , right - left > maxDifference  {
+            maxDifference = right - left
+            waterFilled = (maxLeft * maxRight) - (right - left)
+               print("left = \(left), right = \(right)")
+               print("left waterFilled = \(waterFilled)")
+           }
+           left += 1
+        }
+        else {
+           if (maxLeft * maxRight) - (right - left) >  waterFilled, right - left > maxDifference {
+               maxDifference = right - left
+               waterFilled = (maxLeft * maxRight) - (right - left)
+               print("right waterFilled = \(waterFilled)")
+
+           }
+           right -= 1
+        }
+    }
+    return waterFilled
+}
+
+print("\(maxArea([1,8,6,2,5,4,8,3,7]))")

DataStrucutureQuestions/Array/11. Container With Most Water.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/134. Gas Station.playground/Contents.swift

@@ -17,6 +17,5 @@ func canCompleteCircuit(_ gas: [Int], _ cost: [Int]) -> Int {
      }
      return result
 }
-
 print("starting gas station's index is :- \(canCompleteCircuit([1,2,3,4,5], [3,4,5,1,2]))")
 print("starting gas station's index is :- \(canCompleteCircuit([2,3,4], [3,4,3]))")

DataStrucutureQuestions/Array/14. Longest Common Prefix.playground/Contents.swift

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+import UIKit
+
+//https://leetcode.com/problems/longest-common-prefix/description/?envType=study-plan-v2&envId=top-interview-150
+
+func longestCommonPrefix(_ strs: [String]) -> String {
+    if strs.isEmpty { return ""}
+    if strs.count == 1 { return strs.last! }
+    let sortedArray = strs.sorted()
+    var output = ""
+    for (char1, char2) in zip(sortedArray.first!, sortedArray.last!) {
+        char1
+        if char1 == char2 {
+            output += String(char1)
+        } else {
+            break
+        }
+    }
+    return output
+}
+
+print("Longest common prefix of [flower, flow, flight] is :- \(longestCommonPrefix(["flower","flow","flight"]))")

DataStrucutureQuestions/Array/14. Longest Common Prefix.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/15. 3Sum.playground/Contents.swift

@@ -0,0 +1,27 @@
+import UIKit
+
+func threeSum(_ nums: [Int]) -> [[Int]] {
+    if nums.count < 3 {
+        return []
+    }
+    var sortedArray = nums.sorted()
+    var result = Set<[Int]>()
+    for index in 0..<sortedArray.count {
+        var lowIndex = index + 1
+        var highIndex = nums.count - 1
+        while lowIndex  < highIndex  {
+            let sum = sortedArray[index] + sortedArray[lowIndex] + sortedArray[highIndex]
+            if sum > 0 {
+                highIndex -= 1
+            } else if sum < 0  {
+                lowIndex += 1
+            } else {
+                result.insert([sortedArray[index], sortedArray[lowIndex], sortedArray[highIndex] ])
+                lowIndex += 1
+                highIndex -= 1
+            }
+        }
+    }
+    return Array(result)
+}
+print("all triplets combination of array [-1,0,1,2,-1,-4] is:  \(threeSum([-1,0,1,2,-1,-4]))")

DataStrucutureQuestions/Array/15. 3Sum.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/167. Two Sum II - Input Array Is Sorted.playground/Contents.swift

@@ -0,0 +1,19 @@
+import UIKit
+
+func twoSum(_ numbers: [Int], _ target: Int) -> [Int] {
+    var lowerIndex = 0, higherIndex = numbers.count - 1
+    while lowerIndex < higherIndex {
+        if numbers[lowerIndex] + numbers[higherIndex] > target {
+            higherIndex -= 1
+        } else if numbers[lowerIndex] + numbers[higherIndex] < target {
+            lowerIndex += 1
+        } else {
+            return [lowerIndex + 1, higherIndex + 1]
+        }
+    }
+    return []
+}
+
+print("\(twoSum([2,7,11,15], 9))")
+print("\(twoSum([2,3,4], 6))")
+print("\(twoSum([-1,0], -1))")

DataStrucutureQuestions/Array/167. Two Sum II - Input Array Is Sorted.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/209. Minimum Size Subarray Sum.playground/Contents.swift

@@ -0,0 +1,20 @@
+import UIKit
+
+//https://leetcode.com/problems/minimum-size-subarray-sum/description/?envType=study-plan-v2&envId=top-interview-150
+//Time Complexity O(n)
+
+func minSubArrayLen(_ target: Int, _ nums: [Int]) -> Int {
+     var left = 0, total = 0
+     var result = Int.max
+     for right in 0..<nums.count {
+         total += nums[right]
+         while total >= target {
+             result = min(right - left + 1, result)
+             total -= nums[left]
+             left += 1
+         }
+     }
+     return result == Int.max ? 0 : result
+}
+
+print("minimum window subarray of target 7 is \(minSubArrayLen(7, [2,3,1,2,4,3]))" )

DataStrucutureQuestions/Array/209. Minimum Size Subarray Sum.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/239. Sliding Window Maximum.playground/Contents.swift

@@ -0,0 +1,59 @@
+import UIKit
+
+//https://leetcode.com/problems/sliding-window-maximum/
+
+/*Example :-
+ What should be the output if the following input is given?
+ nums = [1, 2, 3, 1, 4, 5, 2, 3, 6]
+ w = 3  
+ 
+ Ans :-  The first window of size 3 is [1, 2, 3], and the maximum in this window is 3. The second window of size is [2, 3, 1], and the maximum in this window is also 3. The third window of size 3 is [3, 1, 4], and the maximum in this window is 4. The fourth window of size 3 is [1, 4, 5], and the maximum in this window is 5. The fifth window of size 3 is [4, 5, 2], and the maximum in this window is also 5. The sixth window of size 3 is [5, 2, 3], and the maximum in this window is also 5. The seventh and the last window of size 3 is [2, 3, 6], and the maximum in this window is 6.
+  = [3, 3, 4, 5, 5, 5, 6]
+ */
+
+//func maxSlidingWindow(_ nums: [Int], _ k: Int) -> [Int] {
+//     var maxValue = 0
+//     var windowArray : [Int] = []
+//    var maxSlidingWindow : [Int] = []
+//    var start = 0
+//    while start < nums.count {
+//        if start == 0 {
+//            for wIndex in start..<k {
+//                windowArray.append(nums[wIndex])
+//                maxValue = max(maxValue, nums[wIndex])
+//            }
+//            maxSlidingWindow.append(maxValue)
+//            start += k
+//            print(start)
+//        } else {
+//            windowArray.removeFirst()
+//            windowArray.append(nums[start])
+//            maxValue = max(maxValue, nums[start])
+//            maxSlidingWindow.append(maxValue)
+//            start += 1
+//        }
+//    }
+//    return maxSlidingWindow
+//}
+
+func maxSlidingWindow(_ nums: [Int], _ k: Int) -> [Int] {
+    guard nums.isEmpty == false else { return [] }
+    
+    var windowArray = [Int]()
+    var outputArray = [Int]()
+    
+    for i in 0..<nums.count {
+        while (windowArray.count > 0) && (nums[windowArray.last!] < nums[i]) {
+            windowArray.removeLast()
+        }
+        windowArray.append(i)
+        
+        if i >= k - 1 {
+            if windowArray.first! + k == i { windowArray.removeFirst() }
+            outputArray.append(nums[windowArray.first!])
+        }
+    }
+    return outputArray
+}
+
+print(maxSlidingWindow([1,3,-1,-3,5,3,6,7], 3))

DataStrucutureQuestions/Array/239. Sliding Window Maximum.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/Matrix/1706. Where Will the Ball Fall.playground/Contents.swift

@@ -0,0 +1,31 @@
+import UIKit
+
+//https://leetcode.com/problems/where-will-the-ball-fall/
+
+//Time complexity :- O(m * n) Here, mis the number of rows, and n is the number of columns.
+//SpaceComplexity : O(1)
+
+func findBall(_ grid: [[Int]]) -> [Int] {
+    var result = Array(repeating: -1, count: grid[0].count)
+    
+    for col in 0..<grid[0].count {
+        var current_col = col
+        
+        for row in 0..<grid.count {
+            let next_col = current_col + grid[row][current_col]
+            
+            if next_col < 0 || next_col > grid[0].count - 1 || grid[row][current_col] != grid[row][next_col] {
+                break
+            }
+            if row == grid.count - 1 {
+                result[col] = next_col
+            }
+            current_col = next_col
+        }
+    }
+    return result
+}
+print("--FIND BALL FALL EXAMPLE--")
+print(findBall([[1,1,1,-1,-1],[1,1,1,-1,-1],[-1,-1,-1,1,1],[1,1,1,1,-1],[-1,-1,-1,-1,-1]]))
+print(findBall([[1,1,1,1,1,1],[-1,-1,-1,-1,-1,-1],[1,1,1,1,1,1],[-1,-1,-1,-1,-1,-1]]))
+

DataStrucutureQuestions/Matrix/1706. Where Will the Ball Fall.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/Matrix/48. Rotate Image.playground/Contents.swift

@@ -0,0 +1,3 @@
+import UIKit
+
+

DataStrucutureQuestions/Matrix/48. Rotate Image.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/Matrix/73. Set Matrix Zeroes.playground/Contents.swift

@@ -0,0 +1,63 @@
+import UIKit
+
+//https://leetcode.com/problems/set-matrix-zeroes/
+
+
+func setZeroes(_ matrix: inout [[Int]]) {
+    var rows = matrix.count
+    var columns = matrix[0].count
+    var fRow = false
+    var fColumn = false
+    
+    for i in 0..<rows {
+        if matrix[i][0] == 0 {
+            fColumn = true
+        }
+    }
+    
+    for j in 0..<columns {
+        if matrix[0][j] == 0 {
+            fRow = true
+        }
+    }
+    
+    for row in 1..<rows {
+        for col in 1..<columns {
+            if matrix[row][col] == 0 {
+                matrix[0][col] = 0
+                matrix[row][0] = 0
+            }
+        }
+    }
+    
+    for row in 1..<rows {
+        if matrix[row][0] == 0 {
+            for col in 1..<columns {
+                matrix[row][col] = 0
+            }
+        }
+    }
+    
+    for col in 1..<columns {
+        if matrix[0][col] == 0 {
+            for row in 1..<rows {
+                matrix[row][col] = 0
+            }
+        }
+    }
+    
+    if fColumn == true {
+        for row in 0..<rows {
+            matrix[row][0] = 0
+        }
+    }
+    
+    if fRow == true {
+        for col in 0..<columns {
+            matrix[0][col] = 0
+        }
+    }
+}
+var matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]]//   [[1,1,1],[1,0,1],[1,1,1]]
+setZeroes(&matrix)
+print(matrix)

DataStrucutureQuestions/Matrix/73. Set Matrix Zeroes.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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/String/187. Repeated DNA Sequences.playground/Contents.swift

@@ -0,0 +1,39 @@
+import UIKit
+
+//https://leetcode.com/problems/repeated-dna-sequences/description/
+//The average case time complexity of this solution is O(n), where n is the length of the input string.
+func find_repeated_sequences(s: String, k: Int) -> [String] {
+    let window_size = k
+    if s.count <= window_size {
+        return []
+    }
+    let base = 4
+    let hi_place_value = pow(Double(base), Double(window_size - 1))
+    let mapping: [Character: Int] = ["A": 1, "C": 2, "G": 3, "T": 4]
+    var numbers: [Int] = []
+    for char in s {
+        numbers.append(mapping[char]!)
+    }
+    var hashing = 0
+    var substring_hashes: Set<Int> = []
+    var output: Set<String> = []
+    for start in 0..<(s.count - window_size + 1) {
+        if start != 0 {
+            hashing = (hashing - numbers[start - 1] * Int(hi_place_value)) * base
+                + numbers[start + window_size - 1]
+        } else {
+            for end in 0..<window_size {
+                hashing = hashing * base + numbers[end]
+            }
+        }
+        if substring_hashes.contains(hashing) {
+            output.insert(String(s[s.index(s.startIndex, offsetBy: start)..<s.index(s.startIndex, offsetBy: start + window_size)]))
+        }
+        substring_hashes.insert(hashing)
+    }
+    return Array(output)
+}
+
+print(find_repeated_sequences(s: "AAAAACCCCCAAAAACCCCCC", k: 10))
+//print(pow(4.00, 9.00) + pow(4.00, 8.00) + pow(4.00, 7.00) + pow(4.00, 6.00) + pow(4.00, 5.00) + (pow(4.00, 4.00) * 2) + (pow(4.00, 3.00) * 2) + (pow(4.00, 2.00) * 2) + (pow(4.00, 1.00) * 2) + (pow(4.00, 0.00) * 2) )
+print(find_repeated_sequences(s: "AGACCTAGAC", k: 10))

DataStrucutureQuestions/String/187. Repeated DNA Sequences.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?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>