[String] Update Longest Substring with at most 2/k Distinct Characters and Minimum Window Substring

Author: soapyigu

README.md

@@ -69,9 +69,7 @@
 [Gas Station](https://leetcode.com/problems/gas-station/)| [Swift](./Array/GasStation.swift)| Medium| O(n)| O(1)|
 [Game of Life](https://leetcode.com/problems/game-of-life/)| [Swift](./Array/GameLife.swift)| Medium| O(n)| O(1)|
 [Task Scheduler](https://leetcode.com/problems/task-scheduler/)| [Swift](./Array/TaskScheduler.swift)| Medium| O(nlogn)| O(n)|
-[Sliding Window Maximum ](https://leetcode.com/problems/sliding-window-maximum/)| [Swift](./Array/SlidingWindowMaximum.swift)| Hard| O(n)| O(n)|
-[Longest Substring with At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters/)| [Swift](./Array/LongestSubstringMostTwoDistinctCharacters.swift)| Hard| O(n)| O(n)|
-[Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/)| [Swift](./Array/LongestSubstringMostKDistinctCharacters.swift)| Hard| O(n)| O(n)|	
+[Sliding Window Maximum ](https://leetcode.com/problems/sliding-window-maximum/)| [Swift](./Array/SlidingWindowMaximum.swift)| Hard| O(n)| O(n)|	
 [Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/)| [Swift](./Array/LongestConsecutiveSequence.swift)| Hard| O(n)| O(n)|
 
 
@@ -104,6 +102,8 @@
 [One Edit Distance](https://leetcode.com/problems/one-edit-distance/)| [Swift](./String/OneEditDistance.swift)| Medium| O(n)| O(n)|
 [Word Pattern](https://leetcode.com/problems/word-pattern/)| [Swift](./String/WordPattern.swift)| Easy| O(n)| O(n)|
 [Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/)| [Swift](./Array/MinimumWindowSubstring.swift)| Hard| O(n^2)| O(n)|
+[Longest Substring with At Most Two Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters/)| [Swift](./String/LongestSubstringMostTwoDistinctCharacters.swift)| Hard| O(n)| O(n)|
+[Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/)| [Swift](./String/LongestSubstringMostKDistinctCharacters.swift)| Hard| O(n)| O(n)|
 [Text Justification](https://leetcode.com/problems/text-justification/)| [Swift](./String/TextJustification.swift)| Hard| O(n)| O(n)|
 
 ## Linked List
@@ -472,7 +472,7 @@
 |	[Swift](./Math/IntegerBreak.swift)	|	343	|	[Integer Break](https://leetcode.com/problems/integer-break/)	|	Medium
 |		|	342	|	[Power of Four](https://leetcode.com/problems/power-of-four/)	| Easy
 |		|	341	|	[Flatten Nested List Iterator](https://leetcode.com/problems/flatten-nested-list-iterator/)	|	Medium
-|	[Swift](./Array/LongestSubstringMostKDistinctCharacters.swift)	|	340	|	[Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/)  ♥	|	Hard
+|	[Swift](./String/LongestSubstringMostKDistinctCharacters.swift)	|	340	|	[Longest Substring with At Most K Distinct Characters](https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/)  ♥	|	Hard
 |	[Swift](./DP/NestedListWeightSum.swift)	|	339	|	[Nested List Weight Sum](https://leetcode.com/problems/nested-list-weight-sum/)  ♥	| Easy
 |	[Swift](./Math/CountingBits.swift)	|	338	|	[Counting Bits](https://leetcode.com/problems/counting-bits/)	|	Medium
 |		|	337	|	[House Robber III](https://leetcode.com/problems/house-robber-iii/)	|	Medium
@@ -636,7 +636,7 @@
 |	[Swift](./Search/FindPeakElement.swift)	|	162	|	[Find Peak Element](https://oj.leetcode.com/problems/find-peak-element/)	| Medium	|
 |	[Swift](./String/OneEditDistance.swift)	|	161	|	[One Edit Distance](https://oj.leetcode.com/problems/one-edit-distance/)♥	| Medium	|
 |		|	160	|	[Intersection of Two Linked Lists](https://oj.leetcode.com/problems/intersection-of-two-linked-lists/)	| Easy	|
-|	[Swift](./Array/LongestSubstringMostTwoDistinctCharacters.swift)	|	159	|	[Longest Substring with At Most Two Distinct Characters](https://oj.leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters/) ♥	| Hard	|
+|	[Swift](./String/LongestSubstringMostTwoDistinctCharacters.swift)	|	159	|	[Longest Substring with At Most Two Distinct Characters](https://oj.leetcode.com/problems/longest-substring-with-at-most-two-distinct-characters/) ♥	| Hard	|
 |		|	158	|	[Read N Characters Given Read4 II - Call multiple times](https://oj.leetcode.com/problems/read-n-characters-given-read4-ii-call-multiple-times/) ♥	| Hard	|
 |		|	157	|	[Read N Characters Given Read4](https://oj.leetcode.com/problems/read-n-characters-given-read4/) ♥	| Easy	|
 |	[Swift](./Tree/BinaryTreeUpsideDown) |	156	|	[Binary Tree Upside Down](https://oj.leetcode.com/problems/binary-tree-upside-down/) ♥	| Medium	|

Array/LongestSubstringMostKDistinctCharacters.swift renamed to String/LongestSubstringMostKDistinctCharacters.swift

@@ -10,8 +10,8 @@
 class MinimumWindowSubstring {
 
     func minWindow(_ s: String, _ t: String) -> String {
-        var tFreqs = Dictionary(Array(t).map { ($0, 1) }, uniquingKeysWith: +), count = 0
-        var sChars = Array(s), tChars = Array(t), res = "", start = 0
+        var tFreqs = Dictionary(t.map { ($0, 1) }, uniquingKeysWith: +), count = 0
+        var sChars = Array(s), res = "", start = 0
 
         for (i, sChar) in sChars.enumerated() {
             guard let freq = tFreqs[sChar] else {
@@ -24,7 +24,7 @@ class MinimumWindowSubstring {
                 count += 1
             }
 
-            while count == tChars.count {
+            while count == t.count {
                 // jump over redundants
                 guard let startFreq = tFreqs[sChars[start]] else {
                     start += 1