From ea13bb2d2ef23790fa775386537692650b3cbc6c Mon Sep 17 00:00:00 2001 From: "435962415@qq.com" Date: Fri, 23 Feb 2024 12:00:50 +0800 Subject: [PATCH 1/4] =?UTF-8?q?=C2=96827.=E6=9C=80=E5=A4=A7=E4=BA=BA?= =?UTF-8?q?=E5=B7=A5=E5=B2=9B=20=E6=B7=BB=E5=8A=A0go=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0827.最大人工岛.md | 91 ++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) diff --git a/problems/0827.最大人工岛.md b/problems/0827.最大人工岛.md index 4feb78de..cac67676 100644 --- a/problems/0827.最大人工岛.md +++ b/problems/0827.最大人工岛.md @@ -346,6 +346,97 @@ class Solution: return res +``` + +### Go + +```go +func largestIsland(grid [][]int) int { + dir := [][]int{{0, 1}, {1, 0}, {-1, 0}, {0, -1}} + n := len(grid) + m := len(grid[0]) + area := 0 + visited := make([][]bool, n) + for i := 0; i < n; i++ { + visited[i] = make([]bool, m) + } + gridNum := make(map[int]int, 0) // 记录每一个岛屿的面积 + mark := 2 // 记录每个岛屿的编号 + isAllGrid := true + res := 0 // 标记是否整个地图都是陆地 + + var dfs func(grid [][]int, visited [][]bool, x, y, mark int) + dfs = func(grid [][]int, visited [][]bool, x, y, mark int) { + // 终止条件：访问过的节点 或者 遇到海水 + if visited[x][y] || grid[x][y] == 0 { + return + } + visited[x][y] = true // 标记访问过 + grid[x][y] = mark // 给陆地标记新标签 + area++ + for i := 0; i < 4; i++ { + nextX := x + dir[i][0] + nextY := y + dir[i][1] + if nextX < 0 || nextX >= len(grid) || nextY < 0 || nextY >= len(grid[0]) { + continue + } + dfs(grid, visited, nextX, nextY, mark) + } + } + + for i := 0; i < n; i++ { + for j := 0; j < m; j++ { + if grid[i][j] == 0 { + isAllGrid = false + } + if !visited[i][j] && grid[i][j] == 1 { + area = 0 + dfs(grid, visited, i, j, mark) // 将与其链接的陆地都标记上 true + gridNum[mark] = area // 记录每一个岛屿的面积 + mark++ // 更新下一个岛屿编号 + } + } + } + if isAllGrid { + return n * m + } + // 根据添加陆地的位置，计算周边岛屿面积之和 + visitedGrid := make(map[int]struct{}) // 标记访问过的岛屿 + for i := 0; i < n; i++ { + for j := 0; j < m; j++ { + count := 1 // 记录连接之后的岛屿数量 + visitedGrid = make(map[int]struct{}) // 每次使用时，清空 + if grid[i][j] == 0 { + for k := 0; k < 4; k++ { + // 计算相邻坐标 + nearI := i + dir[k][0] + nearJ := j + dir[k][1] + if nearI < 0 || nearI >= len(grid) || nearJ < 0 || nearJ >= len(grid[0]) { + continue + } + // 添加过的岛屿不要重复添加 + if _, ok := visitedGrid[grid[nearI][nearJ]]; ok { + continue + } + // 把相邻四面的岛屿数量加起来 + count += gridNum[grid[nearI][nearJ]] + // 标记该岛屿已经添加过 + visitedGrid[grid[nearI][nearJ]] = struct{}{} + } + } + res = max827(res, count) + } + } + return res +} + +func max827(x, y int) int { + if x > y { + return x + } + return y +} + ```

From b4f55e72745f4f6fbf27dd4bdb2201f1b430b9f2 Mon Sep 17 00:00:00 2001 From: zhangchang Date: Sat, 24 Feb 2024 22:46:14 +0800 Subject: [PATCH 2/4] =?UTF-8?q?=E4=BC=98=E5=8C=96Python=E9=80=92=E5=BD=92?= =?UTF-8?q?=E6=97=B6=E6=89=80=E9=9C=80=E8=A6=81=E7=9A=84=E5=86=85=E5=AD=98?= =?UTF-8?q?=E5=BC=80=E9=94=80=E5=92=8C=E6=97=B6=E9=97=B4=E6=B6=88=E8=80=97?= =?UTF-8?q?=E3=80=82?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/二叉树的递归遍历.md | 54 +++++++++++++++++----------- 1 file changed, 33 insertions(+), 21 deletions(-) diff --git a/problems/二叉树的递归遍历.md b/problems/二叉树的递归遍历.md index edd55aad..4621d4a7 100644 --- a/problems/二叉树的递归遍历.md +++ b/problems/二叉树的递归遍历.md @@ -180,26 +180,34 @@ class Solution { class Solution: def preorderTraversal(self, root: TreeNode) -> List[int]: - if not root: - return [] - - left = self.preorderTraversal(root.left) - right = self.preorderTraversal(root.right) - - return [root.val] + left + right + res = [] + + def dfs(node): + if node is None: + return + + res.append(node.val) + dfs(node.left) + dfs(node.right) + + return res ``` ```python # 中序遍历-递归-LC94_二叉树的中序遍历 class Solution: def inorderTraversal(self, root: TreeNode) -> List[int]: - if root is None: - return [] - - left = self.inorderTraversal(root.left) - right = self.inorderTraversal(root.right) - - return left + [root.val] + right + res = [] + + def dfs(node): + if node is None: + return + + dfs(node.left) + res.append(node.val) + dfs(node.right) + + return res ``` ```python @@ -207,13 +215,17 @@ class Solution: # 后序遍历-递归-LC145_二叉树的后序遍历 class Solution: def postorderTraversal(self, root: TreeNode) -> List[int]: - if not root: - return [] - - left = self.postorderTraversal(root.left) - right = self.postorderTraversal(root.right) - - return left + right + [root.val] + res = [] + + def dfs(node): + if node is None: + return + + dfs(node.left) + dfs(node.right) + res.append(node.val) + + return res ``` ### Go： From f5fc6baddca9af176b77648229ae26fd4bae137e Mon Sep 17 00:00:00 2001 From: meifannao Date: Sun, 25 Feb 2024 22:12:35 +0800 Subject: [PATCH 3/4] =?UTF-8?q?0647.=E5=9B=9E=E6=96=87=E5=AD=90=E4=B8=B2?= =?UTF-8?q?=E6=B7=BB=E5=8A=A0Golang=E7=9A=84=E5=8F=8C=E6=8C=87=E9=92=88?= =?UTF-8?q?=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0647.回文子串.md | 42 +++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/problems/0647.回文子串.md b/problems/0647.回文子串.md index d94d18c5..4887ff83 100644 --- a/problems/0647.回文子串.md +++ b/problems/0647.回文子串.md @@ -397,6 +397,7 @@ class Solution: ``` ### Go： +> 动态规划： ```Go func countSubstrings(s string) int { @@ -422,6 +423,47 @@ func countSubstrings(s string) int { return res } ``` +> 动态规划：简洁版 +```Go +func countSubstrings(s string) int { + res := 0 + dp := make([][]bool, len(s)) + for i := 0; i < len(s); i++ { + dp[i] = make([]bool, len(s)) + } + + for i := len(s) - 1; i >= 0; i-- { + for j := i; j < len(s); j++ { + if s[i] == s[j] && (j-i <= 1 || dp[i+1][j-1]) { + res++ + dp[i][j] = true + } + } + } + return res +} +``` + +> 双指针法： +```Go +func countSubstrings(s string) int { + extend := func(i, j int) int { + res := 0 + for i >= 0 && j < len(s) && s[i] == s[j] { + i -- + j ++ + res ++ + } + return res + } + res := 0 + for i := 0; i < len(s); i++ { + res += extend(i, i) // 以i为中心 + res += extend(i, i+1) // 以i和i+1为中心 + } + return res +} +``` ### Javascript： From 9c5b5676ee221d11280f66b1456ae82822154871 Mon Sep 17 00:00:00 2001 From: Han <90488412+HanCai98@users.noreply.github.com> Date: Sun, 25 Feb 2024 22:48:39 -0500 Subject: [PATCH 4/4] =?UTF-8?q?correct=20typo=20in=200200.=E5=B2=9B?= =?UTF-8?q?=E5=B1=BF=E6=95=B0=E9=87=8F.=E6=B7=B1=E6=90=9C=E7=89=88.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0200.岛屿数量.深搜版.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0200.岛屿数量.深搜版.md b/problems/0200.岛屿数量.深搜版.md index 18442943..83d295bd 100644 --- a/problems/0200.岛屿数量.深搜版.md +++ b/problems/0200.岛屿数量.深搜版.md @@ -37,7 +37,7 @@ 在遇到标记过的陆地节点和海洋节点的时候直接跳过。 这样计数器就是最终岛屿的数量。 -那么如果把节点陆地所能遍历到的陆地都标记上呢，就可以使用 DFS，BFS或者并查集。 +那么如何把节点陆地所能遍历到的陆地都标记上呢，就可以使用 DFS，BFS或者并查集。 ### 深度优先搜索