523_Continuous_Subarray_Sum.swift

+
249_Group_Shifted_Strings.swift

Author: Partho Biswas

README.md

@@ -238,6 +238,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |37| **[763. Partition Labels](https://tinyurl.com/yapt4n6v)** | [Python](https://tinyurl.com/wu6rdaw/763_Partition_Labels.py), [Swift](https://tinyurl.com/wuja3c4/763_Partition_Labels.swift) |  | Medium |  |
 |38| [819. Most Common Word](https://tinyurl.com/ydhwgc33) | [Python](https://tinyurl.com/wu6rdaw/819_Most_Common_Word.py), [Swift](https://tinyurl.com/wuja3c4/819_Most_Common_Word.swift) | [Art 1](https://tinyurl.com/y7u4pzeu) | Easy |  |
 |39| [350. Intersection of Two Arrays II](https://tinyurl.com/y9kdrubz) | [Python](https://tinyurl.com/wu6rdaw/350_Intersection_of_Two_Arrays_II.py), [Swift](https://tinyurl.com/wuja3c4/350_Intersection_of_Two_Arrays_II.swift) | --- | Easy | Check the follow-ups |
+|40| **[249. Group Shifted Strings](https://tinyurl.com/jsfd4l3)** | [Python](https://tinyurl.com/wu6rdaw/249_Group_Shifted_Strings.py), [Swift](https://tinyurl.com/wuja3c4/249_Group_Shifted_Strings.swift) | [Art 1](https://tinyurl.com/yd4ckev2) | Medium | Tricky one |
 
 
 </p>
@@ -716,6 +717,7 @@ BFS, DFS, Dijkstra, Floyd–Warshall, Bellman-Ford, Kruskal, Prim's, Minimum Spa
 |52| **[304. Range Sum Query 2D - Immutable](https://tinyurl.com/ybhblo57)** | [Python](https://tinyurl.com/wu6rdaw/304_Range_Sum_Query_2D_Immutable.py), [Swift](https://tinyurl.com/wuja3c4/304_Range_Sum_Query_2D_Immutable.swift)| [Art 1](https://tinyurl.com/ycto2x5o), [Art 2](https://tinyurl.com/yab7byj5) | Medium | **very good question, classical** |
 |53| **[1477. Find Two Non-overlapping Sub-arrays Each With Target Sum](https://tinyurl.com/ybte7ydl)** | [Python](https://tinyurl.com/wu6rdaw/1477_Find_Two_Non_overlapping_Sub_arrays_Each_With_Target_Sum.py), [Swift](https://tinyurl.com/wuja3c4/1477_Find_Two_Non_overlapping_Sub_arrays_Each_With_Target_Sum.swift)| [Art 1](https://tinyurl.com/y7rshs2j), [Art 2](https://tinyurl.com/y8x7cgxl) | Medium | **Very interesting and deceiving and tricky problem. An unique combination of sliding window and DP** |
 |54| **[368. Largest Divisible Subset](https://tinyurl.com/ya8sv5jr)** | [Python](https://tinyurl.com/wu6rdaw/368_Largest_Divisible_Subset.py), [Swift](https://tinyurl.com/wuja3c4/368_Largest_Divisible_Subset.swift)| Official Solution | Medium | **Interesting problem.** |
+|55| **[523. Continuous Subarray Sum](https://tinyurl.com/y6ce49ln)** | [Python](https://tinyurl.com/wu6rdaw/523_Continuous_Subarray_Sum.py), [Swift](https://tinyurl.com/wuja3c4/523_Continuous_Subarray_Sum.swift)| []() | Medium | **Tricky to see the DP** |
 
 
 </p>

leetcode.com/swift/DS_ALGO_PRAC.playground/Contents.swift

@@ -1,31 +1,7 @@
-import Foundation
-class Solution {
-    func exclusiveTime(_ n: Int, _ logs: [String]) -> [Int] {
-        var funcTimeMap = Array(repeating: 0, count: n)
-        var funcStack = [Int]()
-        var prevTime = 0
-        
-        for log in logs {
-            let logItem = log.split(separator: ":")
-            let (functionOptional, type, timeOptional) = (Int(logItem[0]), logItem[1], Int(logItem[2]))
-            guard let function = functionOptional, let time = timeOptional else {continue}
-            
-            // print("-----")
-            // print("func: \(function), type: \(type), time: \(time), prevTime: \(prevTime)")
-            // print(funcTimeMap)
-            // print(funcStack)
-            
-            if type == "start" {
-                if funcStack = funcStack.count > 0 {
-                    funcTimeMap[funcStack.last!] += (time - prevTime)
-                }
-                prevTime = time
-                funcStack.append(function)
-            } else {
-                funcTimeMap[funcStack.popLast()!] += (time - prevTime + 1)
-                prevTime = time + 1
-            }
-        }
-        return funcTimeMap
-    }
-}
+
+
+
+
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+

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/249_Group_Shifted_Strings.swift

@@ -0,0 +1,22 @@
+import Foundation
+
+extension String {
+    var patternKey: String {
+        let asciiValue = self.unicodeScalars.map {Int($0.value)}
+        let diffValue = asciiValue.map {(26 + $0 - asciiValue[0]) % 26}
+        print("Diff Valets: \(diffValue)")
+        return diffValue.reduce("", {$0 + " \($1)"})
+    }
+}
+
+class Solution {
+    func groupStrings(_ strings: [String]) -> [[String]] {
+        var groupMap = [Int:[String]]()
+        strings.forEach { string in
+            let patttern = string.patternKey
+            print(patttern)
+            groupMap[patttern] = (groupMap[patttern] ?? [String]()) + [string]
+        }
+        return Array(groupMap.values)
+    }
+}

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/523_Continuous_Subarray_Sum.swift

@@ -0,0 +1,28 @@
+/*
+// Initial solution. Time complexity: O(n^2)
+import Foundation
+class Solution {
+    func checkSubarraySum(_ nums: [Int], _ k: Int) -> Bool {
+        guard nums.count > 1 else {return false}
+        
+        for i in (0..<(nums.count) - 1) {
+            var currentSum = nums[i]
+            for j in ((i + 1)..<nums.count) {
+                currentSum += nums[j]
+                if k == 0 {
+                    if currentSum == 0 {
+                        print("1")
+                        return true
+                    } else {
+                        continue
+                    }
+                } else if currentSum % abs(k) == 0 {
+                    print("3")
+                    return true
+                }
+            }
+        }
+        return false
+    }
+}
+ */