yasinshaw
4247e0700d
Changes: - Removed all Java code implementations - Kept only Go language solutions - Renamed "## Go 解法" to "## 解法" - Removed "### Go 代码要点" sections - Cleaned up duplicate headers and empty sections - Streamlined documentation for better readability Updated files (9): - 三数之和.md - 两数相加.md - 无重复字符的最长子串.md - 最长回文子串.md - 括号生成.md - 子集.md - 单词搜索.md - 电话号码的字母组合.md - 柱状图中最大的矩形.md All 22 LeetCode Hot 100 Medium problems now use Go exclusively. Code is cleaner, more focused, and easier to follow. Generated with [Claude Code](https://claude.ai/code) via [Happy](https://happy.engineering) Co-Authored-By: Claude <noreply@anthropic.com> Co-Authored-By: Happy <yesreply@happy.engineering>
115 lines
2.5 KiB
Markdown
115 lines
2.5 KiB
Markdown
# 单词搜索 (Word Search)
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## 题目描述
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给定一个 `m x n` 二维字符网格 `board` 和一个字符串单词 `word`。如果 `word` 存在于网格中，返回 `true`；否则，返回 `false`。
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单词必须按照字母顺序，通过相邻的单元格内的字母构成，其中"相邻"单元格是那些水平相邻或垂直相邻的单元格。同一个单元格内的字母不允许被重复使用。
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### 示例
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**示例 1：**
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```
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输入：board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "ABCCED"
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输出：true
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```
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**示例 2：**
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```
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输入：board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "SEE"
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输出：true
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```
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**示例 3：**
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```
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输入：board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "ABCB"
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输出：false
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```
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## 解题思路
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### 方法一：DFS + 回溯（推荐）
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**核心思想：**对每个位置进行 DFS，搜索是否存在匹配的单词路径。
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**算法步骤：**
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1. 遍历网格的每个位置
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2. 如果当前位置字符匹配单词首字符，开始 DFS
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3. DFS 过程中：
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- 标记当前已访问
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- 向四个方向递归搜索
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- 如果找到完整单词，返回 true
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- 回溯时撤销访问标记
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## 代码实现
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### Go 实现
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```go
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package main
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func exist(board [][]byte, word string) bool {
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m, n := len(board), len(board[0])
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visited := make([][]bool, m)
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for i := range visited {
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visited[i] = make([]bool, n)
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}
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var dfs func(i, j, k int) bool
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dfs = func(i, j, k int) bool {
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// 找到完整单词
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if k == len(word) {
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return true
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}
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// 边界检查或不匹配
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if i < 0 || i >= m || j < 0 || j >= n ||
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visited[i][j] || board[i][j] != word[k] {
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return false
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}
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// 标记访问
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visited[i][j] = true
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// 向四个方向搜索
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found := dfs(i+1, j, k+1) ||
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dfs(i-1, j, k+1) ||
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dfs(i, j+1, k+1) ||
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dfs(i, j-1, k+1)
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// 回溯：取消标记
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visited[i][j] = false
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return found
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}
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for i := 0; i < m; i++ {
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for j := 0; j < n; j++ {
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if board[i][j] == word[0] && dfs(i, j, 0) {
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return true
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}
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}
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}
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return false
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}
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```
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**LeetCode 212:** 给定一个 m x n 二维字符网格 board 和一个单词列表 words，返回所有在二维网格和字典中出现的单词。
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```go
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func findWords(board [][]byte, words []string) []string {
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// 构建 Trie 树
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trie := buildTrie(words)
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result := []string{}
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for i := 0; i < len(board); i++ {
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for j := 0; j < len(board[0]); j++ {
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dfsBoard(board, i, j, trie, &result)
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}
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}
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return result
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}
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```
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