[나리] WEEK 05 Solutions

best-time-to-buy-and-sell-stock/naringst.js

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+/**
+ * @param {number[]} prices
+ * @return {number}
+ */
+
+/**
+ * Runtime: 73ms, Memory: 59.38MB
+ * n = prices.length
+ * Time complexity: O(n)
+ * Space complexity: O(1)
+ *
+ */
+
+var maxProfit = function (prices) {
+  let minPrice = prices[0];
+  let maxPrice = prices[0];
+  let answer = 0;
+
+  for (let i = 1; i < prices.length; i++) {
+    answer = Math.max(answer, maxPrice - minPrice);
+
+    // 가장 뒤쪽 값이 max일 때
+    if (maxPrice < prices[i]) {
+      maxPrice = prices[i];
+      answer = Math.max(answer, maxPrice - minPrice);
+      continue;
+    }
+    // 가장 뒷쪽 값이 min일 때
+    if (minPrice > prices[i]) {
+      minPrice = prices[i];
+      maxPrice = prices[i];
+    }
+  }
+  return answer;
+};

group-anagrams/naringst.js

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+/**
+ * @param {string[]} strs
+ * @return {string[][]}
+ */
+
+/**
+ * Runtime: 100ms, Memory: 62.34MB
+ * n = strs.length
+ * k = 문자열의 최대 길이
+ * Time complexity: O(n * k log k)
+ * -> klogk는 길이가 k인 문자열을 sort
+ * -> n은 이걸 각 문자열마다 반복하기 때문
+ *
+ * Space complexity: O(n)
+ *
+ */
+
+var groupAnagrams = function (strs) {
+  let answer = new Map();
+
+  for (let j = 0; j < strs.length; j++) {
+    const sortedWord = strs[j].split("").sort().join("");
+    answer.has(sortedWord)
+      ? answer.set(sortedWord, [...answer.get(sortedWord), strs[j]])
+      : answer.set(sortedWord, [strs[j]]);
+  }
+
+  return Array.from(answer.values());
+};