Merge branch 'DaleStudy:main' into main

Author: daiyongg-kim

3sum/changhyumm.py

@@ -0,0 +1,33 @@
+class Solution:
+    def threeSum(self, nums: List[int]) -> List[List[int]]:
+        # ans = set()
+        # for i in range(len(n)):
+        #     seen = {}
+        #     for j in range(i+1, len(n)):
+        #         complement = -(nums[i] + nums[j])
+        #         if complement in seen:
+        #             ans.add(tuple(sorted([nums[i], nums[j], complement])))
+        #         seen[nums[j]] = j
+        # return [list(triplet) for triplet in ans]
+        # hash + 이중 loop -> O(n^2)
+
+
+        ## 투포인터 활용
+        # sort + loop -> O(nlogn)
+        ans_set = set()
+        nums.sort()
+        for i in range(len(nums)):
+            l = i + 1
+            r = len(nums) - 1
+            while l < r:
+                total = nums[i] + nums[l] + nums[r]
+                if total < 0:
+                    l += 1
+                elif total > 0:
+                    r -= 1
+                else:
+                    # 중복제거
+                    ans_set.add((nums[i], nums[l], nums[r]))
+                    l += 1
+                    r -= 1
+        return list(ans_set)

README.md

@@ -13,6 +13,7 @@
 
 ## 차수
 
+- 6기 (Nov 9, 2025 - Feb 20, 2026): [프로젝트](https://github.com/orgs/DaleStudy/projects/23/views/3), [팀](https://github.com/orgs/DaleStudy/teams/leetcode06)
 - 5기 (Jul 20, 2025 - Nov 1, 2025): [프로젝트](https://github.com/orgs/DaleStudy/projects/16/views/3), [팀](https://github.com/orgs/DaleStudy/teams/leetcode05)
 - 4기 (Mar 30, 2025 - Jul 12, 2025): [프로젝트](https://github.com/orgs/DaleStudy/projects/13/views/3), [팀](https://github.com/orgs/DaleStudy/teams/leetcode04)
 - 3기 (Dec 08, 2024 - Mar 22, 2025): [프로젝트](https://github.com/orgs/DaleStudy/projects/12/views/3), [팀](https://github.com/orgs/DaleStudy/teams/leetcode03)

best-time-to-buy-and-sell-stock/8804who.py

@@ -0,0 +1,13 @@
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        answer = 0
+
+        min_price = prices[0]
+        for price in prices:
+            if min_price>price:
+                min_price=price
+            
+            if answer<price-min_price:
+                answer=price-min_price
+        return answer
+    

climbing-stairs/HYUNAHKO.py

@@ -0,0 +1,27 @@
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        if (n<1 or n>45):
+            return 0
+        
+        def factorial(num):
+            if num <= 1:
+                return 1
+            
+            result = 1 
+            for i in range(2, num+1):
+                result *= i
+            return result 
+
+        steps = 0
+        cur_steps = 1
+        quotient = n // 2
+        k=0
+       
+        for _ in range(quotient+1):  
+            cur_steps = factorial(n-k) / (factorial(k)*factorial(n-2*k))  
+            k+=1
+            steps += cur_steps
+
+        return int(steps)
+
+

climbing-stairs/changhyumm.py

@@ -0,0 +1,12 @@
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        if n <= 1:
+            return 1
+        dp = [0] * n
+        print(dp)
+        dp[0] = 1
+        dp[1] = 2
+
+        for i in range(2, n):
+            dp[i] = dp[i-2] + dp[i-1]
+        return dp[-1]

climbing-stairs/hongseoupyun.py

@@ -20,7 +20,7 @@ def climbStairs(self, n: int) -> int:
 
         prev1 = 1
         prev2 = 2
-        for i in range(n,n+1):
+        for i in range(3,n+1):
             current = prev2 + prev1
             prev1 = prev2
             prev2 = current

climbing-stairs/ymir0804.java

@@ -0,0 +1,22 @@
+class Solution {
+    public int climbStairs(int n) {
+        int result = 0;
+        int first = 1;
+        int second = 2;
+        int third = 3;
+        if (n == 1) {
+            return first;
+        } else if (n == 2) {
+            return second;
+        } else if (n == 3) {
+            return third;
+        }
+
+        for (int i = 4; i <= n; i++) {
+            result = second + third;
+            second = third;
+            third = result;
+        }
+        return result;
+    }
+}

climbing-stairs/youngDaLee.go

@@ -0,0 +1,34 @@
+package youngDaLee
+
+func climbStairs(n int) int {
+	if n <= 2 {
+		return n
+	}
+
+	dp := make([]int, n+1)
+	dp[1] = 1
+	dp[2] = 2
+
+	for i := 3; i <= n; i++ {
+		dp[i] = dp[i-1] + dp[i-2]
+	}
+	return dp[n]
+}
+
+/*
+Limit Exceeded
+func climbStairs(n int) int {
+	return dfs(0, n)
+}
+
+func dfs(now, n int) int {
+	if now > n {
+		return 0
+	}
+	if now == n {
+		return 1
+	}
+
+	return dfs(now+1, n) + dfs(now+2, n)
+}
+*/

coin-change/8804who.py

@@ -0,0 +1,13 @@
+class Solution:
+    def coinChange(self, coins: List[int], amount: int) -> int:
+        dp = [1e9] * (amount+1)
+        dp[0] = 0
+        
+        for i in range(1, amount+1):
+            for coin in coins:
+                if i-coin>=0:
+                    if dp[i-coin]+1<dp[i]:
+                        dp[i]=dp[i-coin]+1
+        
+        return -1 if dp[amount]==1e9 else dp[amount]
+    

coin-change/Blossssom.ts

@@ -0,0 +1,29 @@
+/**
+ * @param coins - 동전 종류 배열
+ * @param amount - 총 금액
+ * @returns - 총 사용 코인 갯수
+ * @description
+ * - 탐욕으로 풀면 최소 동전갯수를 구할 수 없음
+ * - dp 로 풀이
+ * - 1 부터 금액의 코인 사용 갯수를 추가해 가며, 이전에 구해놓은 값과 min 비교
+ */
+function coinChange(coins: number[], amount: number): number {
+  const dp = new Array(amount + 1).fill(Infinity);
+
+  dp[0] = 0;
+
+  for (let i = 1; i <= amount; i++) {
+    for (const coin of coins) {
+      if (i - coin >= 0) {
+        dp[i] = Math.min(dp[i], dp[i - coin] + 1);
+      }
+    }
+  }
+
+  return dp[amount] === Infinity ? -1 : dp[amount];
+}
+
+const coins = [1, 2, 5];
+const amount = 11;
+coinChange(coins, amount);
+