From 209e13cbe1f83bc8cfc3647de6327eb957456a39 Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Sun, 30 Mar 2025 16:17:45 +0900
Subject: [PATCH 01/10] feat: contains-duplicate solution

---
 contains-duplicate/grapefruitgreentealoe.js | 26 +++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 contains-duplicate/grapefruitgreentealoe.js

diff --git a/contains-duplicate/grapefruitgreentealoe.js b/contains-duplicate/grapefruitgreentealoe.js
new file mode 100644
index 000000000..b4ce4dbe0
--- /dev/null
+++ b/contains-duplicate/grapefruitgreentealoe.js
@@ -0,0 +1,26 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+
+/**
+ * 문제설명: 2개 이상 반복되는 값이 있으면 true, 모두 반복되지 않으면 false.
+
+제한사항
+ 1 <= nums.length <= 10^5
+-109 <= nums[i] <= 109
+ */
+
+var containsDuplicate = function (nums) {
+  const numberSet = new Set();
+  //시간 복잡도 O(n)
+  for (i of nums) {
+    if (!numberSet.has(i)) {
+      //공간복잡도 O(n)
+      numberSet.add(i);
+    } else {
+      return true;
+    }
+  }
+  return false;
+};

From 7f4c26438dd08084a0f249c017346abfdec6b49d Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Wed, 2 Apr 2025 13:02:18 +0900
Subject: [PATCH 02/10] =?UTF-8?q?refactor:=20for=EB=AC=B8=20=EB=B3=80?=
 =?UTF-8?q?=EC=88=98=20=EC=84=A0=EC=96=B8=20=EC=8B=9C=20let=20=ED=82=A4?=
 =?UTF-8?q?=EC=9B=8C=EB=93=9C=20=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 contains-duplicate/grapefruitgreentealoe.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contains-duplicate/grapefruitgreentealoe.js b/contains-duplicate/grapefruitgreentealoe.js
index b4ce4dbe0..2bd26ce0a 100644
--- a/contains-duplicate/grapefruitgreentealoe.js
+++ b/contains-duplicate/grapefruitgreentealoe.js
@@ -14,7 +14,7 @@
 var containsDuplicate = function (nums) {
   const numberSet = new Set();
   //시간 복잡도 O(n)
-  for (i of nums) {
+  for (let i of nums) {
     if (!numberSet.has(i)) {
       //공간복잡도 O(n)
       numberSet.add(i);

From 385603722a46ce7c6b7fb09dbe5d100c9ed534ab Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Wed, 2 Apr 2025 18:00:49 +0900
Subject: [PATCH 03/10] feat: two-sum solution

---
 two-sum/grapefruitgreentealoe.js | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 two-sum/grapefruitgreentealoe.js

diff --git a/two-sum/grapefruitgreentealoe.js b/two-sum/grapefruitgreentealoe.js
new file mode 100644
index 000000000..eea4a7810
--- /dev/null
+++ b/two-sum/grapefruitgreentealoe.js
@@ -0,0 +1,24 @@
+/**
+ * 정수 숫자 배열과 정수 target
+ * 숫자 합이 target과 같은 두 숫자의 index를 리턴.
+ * 같은 요소 두번 X. 답은 항상 1개
+ * 정렬필요 X
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+var twoSum = function (nums, target) {
+  //순회. target에서 nums[i]를 뺀 요소를 찾기.
+  //2중포문. 시간복잡도 O(1)~O(N^2)
+  for (let i = 0; i < nums.length; i++) {
+    const subNum = target - nums[i]; // 공간 O(1)
+    for (let j = i + 1; j < nums.length; j++) {
+      if (nums[j] == subNum) {
+        return [i, j];
+      }
+    }
+  }
+};

From 9e20a2f2769a2a4eeb873b2225fa07e03996319c Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Wed, 2 Apr 2025 18:27:40 +0900
Subject: [PATCH 04/10] refactor: two-sum

---
 two-sum/grapefruitgreentealoe.js | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/two-sum/grapefruitgreentealoe.js b/two-sum/grapefruitgreentealoe.js
index eea4a7810..b663491ed 100644
--- a/two-sum/grapefruitgreentealoe.js
+++ b/two-sum/grapefruitgreentealoe.js
@@ -22,3 +22,27 @@ var twoSum = function (nums, target) {
     }
   }
 };
+
+var twoSum2 = function (nums, target) {
+  for (let i = 0; i < nums.length; i++) {
+    //시간복잡도 O(N)
+    const subNum = target - nums[i]; // 공간 O(1)
+    if (nums.includes(subNum) && nums.indexOf(subNum) !== i) {
+      //시간복잡도 O(N). 2중포문과 같은 효과.
+      return [i, nums.indexOf(subNum)];
+    }
+  }
+};
+
+//Better answer
+var twoSum3 = function (nums, target) {
+  // map으로 관리하여 indexing 최적화
+  const numMap = new Map();
+  for (let i = 0; i < nums.length; i++) {
+    const subNum = target - nums[i];
+    if (numMap.has(subNum)) {
+      return [i, numMap.get(subNum)];
+    }
+    numMap.set(nums[i], i);
+  }
+};

From 9bbc17be96dbe21f924e5ff19bb2d02621c0f2bc Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Wed, 2 Apr 2025 18:47:40 +0900
Subject: [PATCH 05/10] =?UTF-8?q?chore:=20two-sum=20=EC=8B=9C=EA=B0=84,=20?=
 =?UTF-8?q?=EA=B3=B5=EA=B0=84=EB=B3=B5=EC=9E=A1=EB=8F=84=20=EC=A3=BC?=
 =?UTF-8?q?=EC=84=9D=20=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 two-sum/grapefruitgreentealoe.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/two-sum/grapefruitgreentealoe.js b/two-sum/grapefruitgreentealoe.js
index b663491ed..cce88588a 100644
--- a/two-sum/grapefruitgreentealoe.js
+++ b/two-sum/grapefruitgreentealoe.js
@@ -39,10 +39,12 @@ var twoSum3 = function (nums, target) {
   // map으로 관리하여 indexing 최적화
   const numMap = new Map();
   for (let i = 0; i < nums.length; i++) {
+    //시간복잡도 O(N)
     const subNum = target - nums[i];
     if (numMap.has(subNum)) {
+      //시간복잡도 O(1)
       return [i, numMap.get(subNum)];
     }
-    numMap.set(nums[i], i);
+    numMap.set(nums[i], i); // 공간 O(1)
   }
 };

From 9905453337c32552eaab13438a258284816d90a9 Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Wed, 2 Apr 2025 19:24:20 +0900
Subject: [PATCH 06/10] feat: top-k-frequent-elements solution

---
 .../grapefruitgreentealoe.js                  | 30 +++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 top-k-frequent-elements/grapefruitgreentealoe.js

diff --git a/top-k-frequent-elements/grapefruitgreentealoe.js b/top-k-frequent-elements/grapefruitgreentealoe.js
new file mode 100644
index 000000000..e9717af59
--- /dev/null
+++ b/top-k-frequent-elements/grapefruitgreentealoe.js
@@ -0,0 +1,30 @@
+/**
+ * 정수 array nums , 정수 k가 있을때, 가장 빈도가 높은 숫자 k개 리턴. 순서상관 X
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+
+//nums에 대해서 각 요소에 대해 중복되는 횟수를 구한다. 그리고 내림차순으로 k개 리턴한다.
+
+var topKFrequent = function (nums, k) {
+  const numsFreqMap = new Map(); // O(1)
+
+  // O(n) 시간 / O(n) 공간
+  for (let i = 0; i < nums.length; i++) {
+    const count = (numsFreqMap.get(nums[i]) ?? 0) + 1; // O(1)
+    numsFreqMap.set(nums[i], count); // O(1)
+  }
+
+  const arrFromFreqMap = [...numsFreqMap]; // O(n) 시간 / O(n) 공간
+  arrFromFreqMap.sort((a, b) => b[1] - a[1]); // O(n log n) 시간
+
+  return arrFromFreqMap
+    .map((x) => x[0]) // O(n) 시간 / O(n) 공간
+    .slice(0, k); // O(k) 시간 / O(k) 공간
+};
+
+//O(n) + O(n log n) + O(n) + O(k) = O(n log n)

From d8a48f51587ba3a3a16e3ad5fc50c7b737eca040 Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Fri, 4 Apr 2025 02:42:44 +0900
Subject: [PATCH 07/10] =?UTF-8?q?refactor:=20for=20of=20=EC=97=B0=EC=82=B0?=
 =?UTF-8?q?=EC=9C=BC=EB=A1=9C=20=EC=88=98=EC=A0=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 top-k-frequent-elements/grapefruitgreentealoe.js | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/top-k-frequent-elements/grapefruitgreentealoe.js b/top-k-frequent-elements/grapefruitgreentealoe.js
index e9717af59..29981ee40 100644
--- a/top-k-frequent-elements/grapefruitgreentealoe.js
+++ b/top-k-frequent-elements/grapefruitgreentealoe.js
@@ -14,9 +14,8 @@ var topKFrequent = function (nums, k) {
   const numsFreqMap = new Map(); // O(1)
 
   // O(n) 시간 / O(n) 공간
-  for (let i = 0; i < nums.length; i++) {
-    const count = (numsFreqMap.get(nums[i]) ?? 0) + 1; // O(1)
-    numsFreqMap.set(nums[i], count); // O(1)
+  for (let num of nums) {
+    numsFreqMap.set(num, (numsFreqMap.get(num) ?? 0) + 1);
   }
 
   const arrFromFreqMap = [...numsFreqMap]; // O(n) 시간 / O(n) 공간

From 41af5dbad0cb3146c10acdb3c368677519800c92 Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Fri, 4 Apr 2025 20:28:09 +0900
Subject: [PATCH 08/10] feat: longest-consectuive-sequence solution

---
 .../grapefruitgreentealoe.js                  | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 longest-consecutive-sequence/grapefruitgreentealoe.js

diff --git a/longest-consecutive-sequence/grapefruitgreentealoe.js b/longest-consecutive-sequence/grapefruitgreentealoe.js
new file mode 100644
index 000000000..283c24635
--- /dev/null
+++ b/longest-consecutive-sequence/grapefruitgreentealoe.js
@@ -0,0 +1,27 @@
+/**
+ * 정수 배열 nums
+ * 가장 많이 연속되는 요소의 길이 리턴.
+ * O(n) 시간안에 돌아가는 알고리즘 사용할것.
+ */
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function (nums) {
+  const numSet = new Set(nums);
+  let maxCount = 0;
+  for (let i of numSet) { //n 번 순회
+    // ++ 이전에 연속체크가 되었을 수 있으므로, 이전 숫자가 존재한다면 pass
+    if (numSet.has(i - 1)) continue; //이미 진행 된 연속체크의 경우 하지 않는다.
+    //연속이 되는지 확인해서 있으면 1추가.
+    let length = 0;
+    while (numSet.has(i + length)) {
+      //연속이 끊기는 순간 멈추는 반복문. 즉 for문 전체 통틀어 최대 n번 실행.
+      length++;
+    }
+    maxCount = Math.max(length, maxCount);
+  }
+  return maxCount;
+};
+
+//시간복잡도 O(n) + O(n) = O(n) /공간복잡도 O(n)
\ No newline at end of file

From db96ca42a7975f5483260c93bcd6518b0fcf1e90 Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Fri, 4 Apr 2025 20:30:19 +0900
Subject: [PATCH 09/10] =?UTF-8?q?chore:=20=EC=A3=BC=EC=84=9D?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 longest-consecutive-sequence/grapefruitgreentealoe.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/longest-consecutive-sequence/grapefruitgreentealoe.js b/longest-consecutive-sequence/grapefruitgreentealoe.js
index 283c24635..7b142a0ee 100644
--- a/longest-consecutive-sequence/grapefruitgreentealoe.js
+++ b/longest-consecutive-sequence/grapefruitgreentealoe.js
@@ -10,7 +10,8 @@
 var longestConsecutive = function (nums) {
   const numSet = new Set(nums);
   let maxCount = 0;
-  for (let i of numSet) { //n 번 순회
+  for (let i of numSet) {
+    //n 번 순회
     // ++ 이전에 연속체크가 되었을 수 있으므로, 이전 숫자가 존재한다면 pass
     if (numSet.has(i - 1)) continue; //이미 진행 된 연속체크의 경우 하지 않는다.
     //연속이 되는지 확인해서 있으면 1추가.
@@ -24,4 +25,6 @@ var longestConsecutive = function (nums) {
   return maxCount;
 };
 
-//시간복잡도 O(n) + O(n) = O(n) /공간복잡도 O(n)
\ No newline at end of file
+//시간복잡도 O(n) + O(n) = O(n) /공간복잡도 O(n)
+
+//생각할 지점. 양쪽으로 진행된다면, 시간복잡도 최적화 가능

From 49f3bce2c221f1131ec1054a59e09fd48194efa4 Mon Sep 17 00:00:00 2001
From: grapefruitgreentealoe
 <76976331+grapefruitgreentealoe@users.noreply.github.com>
Date: Sat, 5 Apr 2025 03:40:48 +0900
Subject: [PATCH 10/10] feat: house-robber solution

---
 house-robber/grapefruitgreentealoe.js | 45 +++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 house-robber/grapefruitgreentealoe.js

diff --git a/house-robber/grapefruitgreentealoe.js b/house-robber/grapefruitgreentealoe.js
new file mode 100644
index 000000000..fd7148257
--- /dev/null
+++ b/house-robber/grapefruitgreentealoe.js
@@ -0,0 +1,45 @@
+/**
+ * 도둑이 각 집에 돈의 양이 있는데, 근접한 집은 연결된 보안 시스템이 있다
+ * 두 근접 집이 같은 밤에 강도당하면 경찰에게 연락감
+ * 오늘 경찰에게 연락이 가지 않으면서 훔칠 수 있는 최대 돈 리턴
+ */
+
+/**
+ * 만약 dfs로 구한다면, 시간복잡도는 2^n이 된다
+ */
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+
+//최대값 즉 최적의 해를 구하는 문제. dp를 활용해보자.
+var rob = function (nums) {
+  //배열 크기가 늘어남에 따라, 작은 배열에 대한 결과를 활용하여 계산하는 아이디어.
+  const dp = new Array(nums.length + 1); //공간복잡도 O(n)
+  /**
+  dp[0] = 0; //하나도 없을떄
+  dp[1] = nums[0]; //집이 한곳일때
+  dp[2] = Math.max(dp[1], nums[1]); //집이 한곳일때의 dp값과, 현재 순번의 돈
+  dp[3] = Math.max(dp[2], dp[1] + nums[2]);// 더하지 않으면 이전 결과값, 더하려면 그 전의 결과값에 더하기
+   */
+  for (let i = 2; i < dp.length; i++) {
+    //시간복잡도 O(n)
+    dp[i] = Math.max(dp[i - 1], dp[i - 2] + nums[i - 1]);
+  }
+  return dp[dp.length - 1];
+};
+
+var rob2 = function (nums) {
+  //배열에 저장하지 않고 변수에 바로 담는 방식
+  let prev = 0;
+  let curr = 0;
+  for (let num of nums) {
+    //prev는 이전의 curr값으로, curr값은 이전의 prev + num
+    let tempPrev = prev;
+    prev = curr;
+    curr = Math.max(num + tempPrev, curr);
+  }
+  return curr;
+};
+//공간복잡도를 O(1)로 개선
+