Merge pull request #1841 from std-freejia/main

[std-freejia] week05 solutions

Author: std-freejia

best-time-to-buy-and-sell-stock/std-freejia.java

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+/** 
+ * 121. Best Time to Buy and Sell Stock
+ * 반복문 돌면서 가장 작은 값을 기억해둡니다 
+ * 매번 최소값과의 차이를 비교합니다 
+ */
+class Solution {
+    public int maxProfit(int[] prices) {
+        int maxProfit = 0;
+        int minPrice = Integer.MAX_VALUE;
+
+        for (int price: prices) {
+            if (price < minPrice) { // 최소 값 찾기
+                minPrice = price;
+            }
+            if (price - minPrice > maxProfit) {
+                maxProfit = price - minPrice;
+            }
+        }
+        return maxProfit;
+    }
+}

group-anagrams/std-freejia.java

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+class Solution {
+    public List<List<String>> groupAnagrams(String[] strs) {
+        List<List<String>> answer = new ArrayList<>();
+        // <정렬한 문자, 원본 문자 리스트>
+        HashMap<String, List<String>> map = new HashMap<>();
+
+        for (String str : strs) {
+            char[] arr = str.toCharArray();
+            Arrays.sort(arr);
+            String strKey = String.valueOf(arr);
+            
+            if (!map.containsKey(strKey)) {
+                ArrayList<String> list = new ArrayList<>();
+                list.add(str);
+                map.put(strKey, list);
+            } else {
+                map.get(strKey).add(str);
+            }
+        }
+        answer.addAll(map.values());
+        return answer;
+    }
+}