From 7ddf0b91a594a1bd98c27f50d2c92ab1dc18161c Mon Sep 17 00:00:00 2001 From: CyC2018 Date: Sat, 31 Oct 2026 14:03:47 +0800 Subject: [PATCH] =?UTF-8?q?Update=20Leetcode=20=E9=A2=98=E8=A7=A3=20-=20?= =?UTF-8?q?=E6=90=9C=E7=B4=A2.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 补充复杂度分析；题目链接统一为 leetcode.cn。 --- notes/Leetcode 题解 - 搜索.md | 50 ++++++++++++++++++----------------- 1 file changed, 26 insertions(+), 24 deletions(-) diff --git a/notes/Leetcode 题解 - 搜索.md b/notes/Leetcode 题解 - 搜索.md index 155a05f1..b7dd3a5f 100644 --- a/notes/Leetcode 题解 - 搜索.md +++ b/notes/Leetcode 题解 - 搜索.md @@ -70,7 +70,7 @@ 1091\. Shortest Path in Binary Matrix (Medium) -[Leetcode](https://leetcode.com/problems/shortest-path-in-binary-matrix/) / [力扣](https://leetcode-cn.com/problems/shortest-path-in-binary-matrix/) +[Leetcode](https://leetcode.com/problems/shortest-path-in-binary-matrix/) / [力扣](https://leetcode.cn/problems/shortest-path-in-binary-matrix/) ```text Input: grid = [[0,0,0], @@ -121,7 +121,7 @@ public int shortestPathBinaryMatrix(int[][] grids) { 279\. Perfect Squares (Medium) -[Leetcode](https://leetcode.com/problems/perfect-squares/description/) / [力扣](https://leetcode-cn.com/problems/perfect-squares/description/) +[Leetcode](https://leetcode.com/problems/perfect-squares/description/) / [力扣](https://leetcode.cn/problems/perfect-squares/description/) ```text For example, given n = 12, return 3 because 12 = 4 + 4 + 4; given n = 13, return 2 because 13 = 4 + 9. @@ -186,7 +186,7 @@ private List generateSquares(int n) { 127\. Word Ladder (Hard) -[Leetcode](https://leetcode.com/problems/word-ladder/description/) / [力扣](https://leetcode-cn.com/problems/word-ladder/description/) +[Leetcode](https://leetcode.com/problems/word-ladder/description/) / [力扣](https://leetcode.cn/problems/word-ladder/description/) ```text Input: @@ -301,7 +301,7 @@ private int getShortestPath(List[] graphic, int start, int end) { 695\. Max Area of Island (Medium) -[Leetcode](https://leetcode.com/problems/max-area-of-island/description/) / [力扣](https://leetcode-cn.com/problems/max-area-of-island/description/) +[Leetcode](https://leetcode.com/problems/max-area-of-island/description/) / [力扣](https://leetcode.cn/problems/max-area-of-island/description/) ```text [[0,0,1,0,0,0,0,1,0,0,0,0,0], @@ -352,7 +352,7 @@ private int dfs(int[][] grid, int r, int c) { 200\. Number of Islands (Medium) -[Leetcode](https://leetcode.com/problems/number-of-islands/description/) / [力扣](https://leetcode-cn.com/problems/number-of-islands/description/) +[Leetcode](https://leetcode.com/problems/number-of-islands/description/) / [力扣](https://leetcode.cn/problems/number-of-islands/description/) ```text Input: @@ -399,6 +399,8 @@ private void dfs(char[][] grid, int i, int j) { } ``` +每个格子最多被改为 0 一次，之后对它的 dfs 调用都立即返回，而每个格子最多被 4 个相邻格子各调用一次，时间复杂度 O(MN)；全是 1 时递归深度为 MN，空间复杂度 O(MN)。 + 需要注意的是，递归深度最多等于岛屿的格子数，300 × 300 的网格全是 1 时深达 9 万层，JDK 21 默认的线程栈会溢出（见[附录 A1](#a1-岛屿数量的递归深度)），这时可以把 dfs 换成下面的 BFS： ```java @@ -424,7 +426,7 @@ private void bfs(char[][] grid, int i, int j) { 547\. Number of Provinces (Medium) -[Leetcode](https://leetcode.com/problems/number-of-provinces/description/) / [力扣](https://leetcode-cn.com/problems/number-of-provinces/description/) +[Leetcode](https://leetcode.com/problems/number-of-provinces/description/) / [力扣](https://leetcode.cn/problems/number-of-provinces/description/) ```text Input: @@ -470,7 +472,7 @@ private void dfs(int[][] M, int i, boolean[] hasVisited) { 130\. Surrounded Regions (Medium) -[Leetcode](https://leetcode.com/problems/surrounded-regions/description/) / [力扣](https://leetcode-cn.com/problems/surrounded-regions/description/) +[Leetcode](https://leetcode.com/problems/surrounded-regions/description/) / [力扣](https://leetcode.cn/problems/surrounded-regions/description/) ```text For example, @@ -539,7 +541,7 @@ private void dfs(char[][] board, int r, int c) { 417\. Pacific Atlantic Water Flow (Medium) -[Leetcode](https://leetcode.com/problems/pacific-atlantic-water-flow/description/) / [力扣](https://leetcode-cn.com/problems/pacific-atlantic-water-flow/description/) +[Leetcode](https://leetcode.com/problems/pacific-atlantic-water-flow/description/) / [力扣](https://leetcode.cn/problems/pacific-atlantic-water-flow/description/) ```text Given the following 5x5 matrix: @@ -651,7 +653,7 @@ backtracking(当前选择): 17\. Letter Combinations of a Phone Number (Medium) -[Leetcode](https://leetcode.com/problems/letter-combinations-of-a-phone-number/description/) / [力扣](https://leetcode-cn.com/problems/letter-combinations-of-a-phone-number/description/) +[Leetcode](https://leetcode.com/problems/letter-combinations-of-a-phone-number/description/) / [力扣](https://leetcode.cn/problems/letter-combinations-of-a-phone-number/description/)

@@ -691,7 +693,7 @@ private void doCombination(StringBuilder prefix, List combinations, fina 93\. Restore IP Addresses (Medium) -[Leetcode](https://leetcode.com/problems/restore-ip-addresses/description/) / [力扣](https://leetcode-cn.com/problems/restore-ip-addresses/description/) +[Leetcode](https://leetcode.com/problems/restore-ip-addresses/description/) / [力扣](https://leetcode.cn/problems/restore-ip-addresses/description/) ```text Given "25525511135", @@ -736,7 +738,7 @@ private void doRestore(int k, StringBuilder tempAddress, List addresses, 79\. Word Search (Medium) -[Leetcode](https://leetcode.com/problems/word-search/description/) / [力扣](https://leetcode-cn.com/problems/word-search/description/) +[Leetcode](https://leetcode.com/problems/word-search/description/) / [力扣](https://leetcode.cn/problems/word-search/description/) ```text For example, @@ -809,7 +811,7 @@ private boolean backtracking(int curLen, int r, int c, boolean[][] visited, fina 257\. Binary Tree Paths (Easy) -[Leetcode](https://leetcode.com/problems/binary-tree-paths/description/) / [力扣](https://leetcode-cn.com/problems/binary-tree-paths/description/) +[Leetcode](https://leetcode.com/problems/binary-tree-paths/description/) / [力扣](https://leetcode.cn/problems/binary-tree-paths/description/) ```text 1 @@ -868,7 +870,7 @@ private String buildPath(List values) { 46\. Permutations (Medium) -[Leetcode](https://leetcode.com/problems/permutations/description/) / [力扣](https://leetcode-cn.com/problems/permutations/description/) +[Leetcode](https://leetcode.com/problems/permutations/description/) / [力扣](https://leetcode.cn/problems/permutations/description/) ```text [1,2,3] have the following permutations: @@ -917,7 +919,7 @@ private void backtracking(List permuteList, List> permute 47\. Permutations II (Medium) -[Leetcode](https://leetcode.com/problems/permutations-ii/description/) / [力扣](https://leetcode-cn.com/problems/permutations-ii/description/) +[Leetcode](https://leetcode.com/problems/permutations-ii/description/) / [力扣](https://leetcode.cn/problems/permutations-ii/description/) ```text [1,1,2] have the following unique permutations: @@ -968,7 +970,7 @@ private void backtracking(List permuteList, List> permute 77\. Combinations (Medium) -[Leetcode](https://leetcode.com/problems/combinations/description/) / [力扣](https://leetcode-cn.com/problems/combinations/description/) +[Leetcode](https://leetcode.com/problems/combinations/description/) / [力扣](https://leetcode.cn/problems/combinations/description/) ```text If n = 4 and k = 2, a solution is: @@ -1009,7 +1011,7 @@ private void backtracking(List combineList, List> combina 39\. Combination Sum (Medium) -[Leetcode](https://leetcode.com/problems/combination-sum/description/) / [力扣](https://leetcode-cn.com/problems/combination-sum/description/) +[Leetcode](https://leetcode.com/problems/combination-sum/description/) / [力扣](https://leetcode.cn/problems/combination-sum/description/) ```text given candidate set [2, 3, 6, 7] and target 7, @@ -1047,7 +1049,7 @@ private void backtracking(List tempCombination, List> com 40\. Combination Sum II (Medium) -[Leetcode](https://leetcode.com/problems/combination-sum-ii/description/) / [力扣](https://leetcode-cn.com/problems/combination-sum-ii/description/) +[Leetcode](https://leetcode.com/problems/combination-sum-ii/description/) / [力扣](https://leetcode.cn/problems/combination-sum-ii/description/) ```text For example, given candidate set [10, 1, 2, 7, 6, 1, 5] and target 8, @@ -1096,7 +1098,7 @@ private void backtracking(List tempCombination, List> com 216\. Combination Sum III (Medium) -[Leetcode](https://leetcode.com/problems/combination-sum-iii/description/) / [力扣](https://leetcode-cn.com/problems/combination-sum-iii/description/) +[Leetcode](https://leetcode.com/problems/combination-sum-iii/description/) / [力扣](https://leetcode.cn/problems/combination-sum-iii/description/) ```text Input: k = 3, n = 9 @@ -1138,7 +1140,7 @@ private void backtracking(int k, int n, int start, 78\. Subsets (Medium) -[Leetcode](https://leetcode.com/problems/subsets/description/) / [力扣](https://leetcode-cn.com/problems/subsets/description/) +[Leetcode](https://leetcode.com/problems/subsets/description/) / [力扣](https://leetcode.cn/problems/subsets/description/) 找出集合的所有子集，子集不能重复，[1, 2] 和 [2, 1] 这种子集算重复。 @@ -1173,7 +1175,7 @@ private void backtracking(int start, List tempSubset, List tempSubset, List
@@ -1339,7 +1341,7 @@ private int cubeNum(int i, int j) { 51\. N-Queens (Hard) -[Leetcode](https://leetcode.com/problems/n-queens/description/) / [力扣](https://leetcode-cn.com/problems/n-queens/description/) +[Leetcode](https://leetcode.com/problems/n-queens/description/) / [力扣](https://leetcode.cn/problems/n-queens/description/)

@@ -1407,7 +1409,7 @@ private void backtracking(int row) { 22\. Generate Parentheses (Medium) -[Leetcode](https://leetcode.com/problems/generate-parentheses/description/) / [力扣](https://leetcode-cn.com/problems/generate-parentheses/description/) +[Leetcode](https://leetcode.com/problems/generate-parentheses/description/) / [力扣](https://leetcode.cn/problems/generate-parentheses/description/) ```text Input: n = 3