Merge pull request #1837 from sonjh1217/main

[sonjh1217] WEEK05 solutions

Author: sonjh1217

best-time-to-buy-and-sell-stock/sonjh1217.swift

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+class Solution {
+    func maxProfit(_ prices: [Int]) -> Int {
+        var maxProfit = 0
+        var minPrice = prices[0]
+        
+        for i in (1..<prices.count) {
+            let profit = prices[i] - minPrice
+            maxProfit = max(profit, maxProfit)
+            minPrice = min(prices[i], minPrice)
+        }
+        
+        return maxProfit
+        
+        //시간복잡도 O(n)
+        //공간복잡도 O(1)
+    }
+}
+

group-anagrams/sonjh1217.swift

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+class Solution {
+    func groupAnagrams(_ strs: [String]) -> [[String]] {
+        var stringsByCount = [[Int]: [String]]()
+        
+        strs.map { str in
+            var countsByAlphabet = Array(repeating: 0, count: 26)
+            for char in str.unicodeScalars {
+                countsByAlphabet[Int(char.value) - 97] += 1
+            }
+            stringsByCount[countsByAlphabet, default: []].append(str)
+        }
+        
+        return Array(stringsByCount.values)
+    }
+    //시간 O(n*L) L=string들의 평균 길이
+    //공간 O(n*L)
+}
+