Merge branch 'main' of https://github.com/highballplz/dale-leetcode-study

Author: highballplz

.github/CODEOWNERS

@@ -0,0 +1 @@
+*   @DaleStudy/coach

.github/pull_request_template.md

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+## 답안 제출 문제
+
+<!--
+자신의 수준이나 일정에 맞게 금주에 푸시기로 정한 문제들만 나열해주세요.
+코드 검토자들이 PR 승인 여부를 결정할 때 도움이 됩니다.
+-->
+
+- [ ] 문제 1
+- [ ] 문제 2
+- [ ] 문제 3
+
+## 체크 리스트
+
+- [ ] PR을 프로젝트에 추가하고 Week를 현재 주차로 설정해주세요.
+- [ ] 바로 앞에 PR을 열어주신 분을 코드 검토자로 지정해주세요.
+- [ ] 문제를 모두 푸시면 프로젝트에서 Status를 `In Review`로 설정해주세요.
+- [ ] 코드 검토자 1분 이상으로부터 승인을 받으셨다면 PR을 병합해주세요.

.github/workflows/integration.yaml

@@ -8,4 +8,21 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: fernandrone/[email protected]
+        with:
+          fetch-depth: 0
+
+      - name: Find files missing end line break
+        run: |
+          files=$(git diff --name-only ${{ github.event.pull_request.base.sha }} ${{ github.sha }})
+          success=true
+          for file in $files; do
+            if [ "$(tail -c 1 $file | wc -l)" -eq 0 ]; then
+              echo "- $file" >> $GITHUB_STEP_SUMMARY
+              success=false
+            fi
+          done
+
+          if [ "$success" = false ]; then
+            echo -e "\n:warning: 위 파일들의 끝에 누락된 줄 바꿈을 추가해 주세요." >> $GITHUB_STEP_SUMMARY
+            exit 1
+          fi

climbing-stairs/EGON.py

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+from unittest import TestCase, main
+
+
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        return self.solveWithDP(n)
+
+    """
+    Runtime: 30 ms (Beats 83.62%)
+    Time Complexity: O(n)
+        > 3에서 n + 1 까지 range를 조회하였으므로 O((n + 1) - 3) ~= O(n)
+
+    Memory: 16.39 MB (Beats 90.15%)
+    Space Complexity: O(n)
+        > 크기가 n + 1인 dp를 선언하여 사용했으므로 O(n + 1) ~= O(n)
+    """
+    def solveWithDP(self, n: int) -> int:
+        if n <= 2:
+            return n
+
+        dp = [0] * (n + 1)
+        dp[0], dp[1], dp[2] = 0, 1, 2
+        for stair in range(3, n + 1):
+            dp[stair] = dp[stair - 1] + dp[stair - 2]
+
+        return dp[n]
+
+
+class _LeetCodeTestCases(TestCase):
+    def test_1(self):
+        n = 2
+        output = 2
+        self.assertEqual(Solution.climbStairs(Solution(), n), output)
+
+    def test_2(self):
+        n = 3
+        output = 3
+        self.assertEqual(Solution.climbStairs(Solution(), n), output)
+
+    def test_3(self):
+        n = 1
+        output = 1
+        self.assertEqual(Solution.climbStairs(Solution(), n), output)
+
+
+if __name__ == '__main__':
+    main()

coin-change/EGON.py

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+from typing import List
+from unittest import TestCase, main
+from collections import defaultdict
+
+
+class Solution:
+    def coinChange(self, coins: List[int], amount: int) -> int:
+        return self.solve_with_dp(coins, amount)
+
+    # Unbounded Knapsack Problem
+    def solve_with_dp(self, coins: List[int], amount: int) -> int:
+        if amount == 0:
+            return 0
+
+        coins.sort()
+
+        if amount < coins[0]:
+            return -1
+
+        dp = [[0] * (amount + 1) for _ in range(len(coins) + 1)]
+        for curr_r in range(1, len(coins) + 1):
+            coin_index = curr_r - 1
+            curr_coin = coins[coin_index]
+            if amount < curr_coin:
+                continue
+
+            dp[curr_r][curr_coin] += 1
+            for curr_amount in range(curr_coin + 1, amount + 1):
+                for coin in coins:
+                    if 0 < dp[curr_r][curr_amount - coin]:
+                        dp[curr_r][curr_amount] = max(dp[curr_r - 1][curr_amount], dp[curr_r][curr_amount - coin] + 1)
+                    else:
+                        dp[curr_r][curr_amount] = dp[curr_r - 1][curr_amount]
+
+        return dp[-1][-1] if 0 < dp[-1][-1] else -1
+
+
+class _LeetCodeTestCases(TestCase):
+    def test_1(self):
+        coins = [1, 2, 5]
+        amount = 11
+        output = 3
+        self.assertEqual(Solution.coinChange(Solution(), coins, amount), output)
+
+    def test_2(self):
+        coins = [2]
+        amount = 3
+        output = -1
+        self.assertEqual(Solution.coinChange(Solution(), coins, amount), output)
+
+    def test_3(self):
+        coins = [1]
+        amount = 0
+        output = 0
+        self.assertEqual(Solution.coinChange(Solution(), coins, amount), output)
+
+    def test_4(self):
+        coins = [1, 2147483647]
+        amount = 2
+        output = -1
+        self.assertEqual(Solution.coinChange(Solution(), coins, amount), output)
+
+
+if __name__ == '__main__':
+    main()

combination-sum/EGON.py

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+from typing import List
+from unittest import TestCase, main
+from collections import defaultdict
+
+
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        return self.solve_with_dfs(candidates, target)
+
+    """
+    Runtime: 2039 ms (Beats 5.01%)
+    Time Complexity: ?
+
+    Memory: 16.81 MB (Beats 11.09%)
+    Space Complexity: ?
+    """
+    def solve_with_dfs(self, candidates: List[int], target: int) -> List[List[int]]:
+        result = []
+        stack = []
+        visited = defaultdict(bool)
+        for candidate in candidates:
+            stack.append([[candidate], candidate])
+
+        while stack:
+            curr_combination, curr_sum = stack.pop()
+            curr_visited_checker = tuple(sorted(curr_combination))
+
+            if curr_sum == target and visited[curr_visited_checker] is False:
+                visited[curr_visited_checker] = True
+                result.append(curr_combination)
+
+            if target < curr_sum:
+                continue
+
+            for candidate in candidates:
+                post_combination, post_sum = curr_combination + [candidate], curr_sum + candidate
+                stack.append([post_combination, post_sum])
+
+        return result
+
+
+class _LeetCodeTestCases(TestCase):
+    def test_1(self):
+        candidates = [2, 3, 6, 7]
+        target = 7
+        output = [[2, 2, 3], [7]]
+        self.assertEqual(Solution.combinationSum(Solution(), candidates, target), output)
+
+    def test_2(self):
+        candidates = [2, 3, 5]
+        target = 8
+        output = [[2, 2, 2, 2], [2, 3, 3], [3, 5]]
+        self.assertEqual(Solution.combinationSum(Solution(), candidates, target), output)
+
+    def test_3(self):
+        candidates = [2]
+        target = 1
+        output = []
+        self.assertEqual(Solution.combinationSum(Solution(), candidates, target), output)
+
+
+if __name__ == '__main__':
+    main()

construct-binary-tree-from-preorder-and-inorder-traversal/EGON.py

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+from typing import List, Optional
+from unittest import TestCase, main
+
+
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
+class Solution:
+    def buildTree(self, preorder: List[int], inorder: List[int]) -> Optional[TreeNode]:
+        return self.solve_1(preorder, inorder)
+
+    """
+    Runtime: 112 ms (Beats 66.16%)
+    Time Complexity: O(n ** 2)
+    Space Complexity: O(n)
+    Memory: 52.83 MB (Beats 63.14%)
+    """
+    def solve_1(self, preorder: List[int], inorder: List[int]) -> Optional[TreeNode]:
+        index = 0
+
+        def build_tree(preorder: List[int], inorder: List[int]) -> Optional[TreeNode]:
+            nonlocal index
+
+            if not inorder:
+                return None
+
+            if not 0 <= index < len(preorder):
+                return None
+
+            root = TreeNode(preorder[index])
+            index += 1
+            split_index = inorder.index(root.val)
+            root.left = build_tree(preorder, inorder[:split_index])
+            root.right = build_tree(preorder, inorder[split_index + 1:])
+
+            return root
+
+        return build_tree(preorder, inorder)
+
+
+class _LeetCodeTestCases(TestCase):
+    def test_1(self):
+        preorder = [3, 9, 20, 15, 7]
+        inorder = [9, 3, 15, 20, 7]
+        output = TreeNode(
+            val=3,
+            left=TreeNode(
+                val=9
+            ),
+            right=TreeNode(
+                val=20,
+                left=TreeNode(val=15),
+                right=TreeNode(val=7)
+            )
+        )
+        self.assertEqual(Solution.buildTree(Solution(), preorder, inorder), output)
+
+    def test_2(self):
+        preorder = [-1]
+        inorder = [-1]
+        output = TreeNode(
+            val=-1
+        )
+        self.assertEqual(Solution.buildTree(Solution(), preorder, inorder), output)
+
+    def test_3(self):
+        preorder = [1, 2]
+        inorder = [1, 2]
+        output = TreeNode(
+            val=1,
+            right=TreeNode(
+                val=2
+            )
+        )
+        self.assertEqual(Solution.buildTree(Solution(), preorder, inorder), output)
+
+
+if __name__ == '__main__':
+    main()

construct-binary-tree-from-preorder-and-inorder-traversal/TomyKim9401.java

@@ -0,0 +1,23 @@
+class Solution {
+    private int i, p;
+    public TreeNode buildTree(int[] preorder, int[] inorder) {
+        // Time complexity: O(n)
+        // Space complexity: O(n)
+        return builder(preorder, inorder, Integer.MIN_VALUE);
+    }
+
+    private TreeNode builder(int[] preorder, int[] inorder, int stop) {
+        if (p >= preorder.length) return null;
+        if (inorder[i] == stop) {
+            i += 1;
+            return null;
+        }
+
+        TreeNode node = new TreeNode(preorder[p]);
+        p += 1;
+
+        node.left = builder(preorder, inorder, node.val);
+        node.right = builder(preorder, inorder, stop);
+        return node;
+    }
+}

construct-binary-tree-from-preorder-and-inorder-traversal/coloryourlife.py

@@ -0,0 +1,23 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    # T: O(N)
+    # S: O(N)
+    def buildTree(self, preorder: List[int], inorder: List[int]) -> Optional[TreeNode]:
+        # preorder : root - left - right
+        # inorder : left - root - right
+        if not preorder and not inorder:
+            return None
+        
+        root = TreeNode(preorder[0])
+        mid = inorder.index(preorder[0])
+        
+        root.left = self.buildTree(preorder[1 : mid + 1], inorder[:mid])
+        root.right = self.buildTree(preorder[mid + 1 :], inorder[mid+1:])
+        
+        return root
+