remove pre/next in markdown

Author: halfrost

.github/workflows/deploy.yml

@@ -52,12 +52,16 @@ jobs:
           ./website/public/ \
           "${SSH_USERNAME}@${SSH_HOST}:${SERVER_DESTINATION:-/var/www/books/leetcode/}"
 
-  word-count:   # 重新统计总字数并把 README 里的徽章数字刷新、自动提交回仓库
+  word-count:   # 重新统计总字数，并通过 PR 刷新 README 里的徽章数字
     # 只在 master 上跑（add_hugo 等分支不自动改 README）。
+    # master 是受保护分支（必须走 PR），所以这里不直接 push，而是开/更新一个 PR。
+    # 需要在 Settings → Actions → General → Workflow permissions 勾选
+    # "Allow GitHub Actions to create and approve pull requests"。
     if: github.ref == 'refs/heads/master'
     runs-on: ubuntu-latest
     permissions:
-      contents: write   # 需要写权限才能 commit & push 回仓库
+      contents: write        # 推送 PR 分支
+      pull-requests: write   # 创建/更新 PR
     steps:
     - uses: actions/checkout@v5
 
@@ -72,19 +76,22 @@ jobs:
         echo "total word count = $COUNT"
         echo "count=$COUNT" >> "$GITHUB_OUTPUT"
 
-    - name: Update badge & commit if changed
+    - name: Update badge number in README
       run: |
-        # 只替换 README 里 Total Word Count 徽章的数字部分
-        COUNT="${{ steps.wc.outputs.count }}"
-        sed -i -E "s#(Total%20Word%20Count-)[0-9]+(-success)#\1${COUNT}\2#" README.md
-        if git diff --quiet -- README.md; then
-          echo "徽章已是最新（${COUNT}），无需提交。"
-        else
-          git config user.name  "github-actions[bot]"
-          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
-          git add README.md
-          # [skip ci]：这次只改 README 的自动提交不必再触发任何 workflow（deploy 已 paths-ignore，
-          # 但 test.yml 没有，所以统一用 skip ci 防止多余构建，也彻底杜绝循环触发）。
-          git commit -m "chore: update Total Word Count badge to ${COUNT} [skip ci]"
-          git push
-        fi
+        sed -i -E "s#(Total%20Word%20Count-)[0-9]+(-success)#\1${{ steps.wc.outputs.count }}\2#" README.md
+
+    - name: Open/update PR if the badge changed
+      # 仅当 README 真的变了才会建/更新 PR；固定分支名 chore/word-count-badge，
+      # 始终复用同一个 PR，不会刷屏。合并即可更新徽章。
+      uses: peter-evans/create-pull-request@v6
+      with:
+        add-paths: README.md
+        branch: chore/word-count-badge
+        delete-branch: true
+        commit-message: "chore: update Total Word Count badge to ${{ steps.wc.outputs.count }}"
+        title: "chore: update Total Word Count badge to ${{ steps.wc.outputs.count }}"
+        body: |
+          自动刷新 README 的 Total Word Count 徽章为 **${{ steps.wc.outputs.count }}**
+          （口径：汉字 + 英文单词，已剔除代码块；由 `website/content/ChapterFour/pytool/WordCount.py` 统计）。
+
+          合并即可更新徽章；若数字没变化则不会创建本 PR。

README.md

@@ -488,7 +488,7 @@
 |0348|Design Tic-Tac-Toe||57.6%|Medium||
 |0349|Intersection of Two Arrays|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0349.Intersection-of-Two-Arrays)|70.2%|Easy||
 |0350|Intersection of Two Arrays II|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0350.Intersection-of-Two-Arrays-II)|55.5%|Easy||
-|0351|Android Unlock Patterns||51.3%|Medium||
+|0351|Android Unlock Patterns|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0351.Android-Unlock-Patterns)|51.3%|Medium||
 |0352|Data Stream as Disjoint Intervals|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0352.Data-Stream-as-Disjoint-Intervals)|51.5%|Hard||
 |0353|Design Snake Game||39.0%|Medium||
 |0354|Russian Doll Envelopes|[Go](https://github.com/halfrost/LeetCode-Go/tree/master/leetcode/0354.Russian-Doll-Envelopes)|38.3%|Hard||

ctl/label.go

@@ -123,16 +123,16 @@ func newDeletePreNext() *cobra.Command {
 }
 
 func addPreNext() {
-	// Chpater one add pre-next
-	addPreNextLabel(chapterOneFileOrder, []string{}, []int{}, "", "ChapterOne", "ChapterTwo")
-	// Chpater two add pre-next
-	addPreNextLabel(chapterTwoFileOrder, chapterOneFileOrder, []int{}, "ChapterOne", "ChapterTwo", "ChapterThree")
-	// Chpater three add pre-next
-	addPreNextLabel(chapterThreeFileOrder, chapterTwoFileOrder, []int{}, "ChapterTwo", "ChapterThree", "ChapterFour")
-	// Chpater four add pre-next
-	//fmt.Printf("%v\n", getChapterFourFileOrder())
-	chapterFourFileOrder, solutionIds := getChapterFourFileOrder()
-	addPreNextLabel(chapterFourFileOrder, chapterThreeFileOrder, solutionIds, "ChapterThree", "ChapterFour", "")
+	// 上/下页导航已改由 Hugo 主题在渲染时动态生成
+	// （themes/book/layouts/partials/docs/inject/content-after.html），
+	// 不再把导航 HTML 写进 markdown，避免与主题渲染的导航重复。
+	// 如需恢复写入 markdown 的旧行为，取消下面的注释即可。
+	//
+	// addPreNextLabel(chapterOneFileOrder, []string{}, []int{}, "", "ChapterOne", "ChapterTwo")
+	// addPreNextLabel(chapterTwoFileOrder, chapterOneFileOrder, []int{}, "ChapterOne", "ChapterTwo", "ChapterThree")
+	// addPreNextLabel(chapterThreeFileOrder, chapterTwoFileOrder, []int{}, "ChapterTwo", "ChapterThree", "ChapterFour")
+	// chapterFourFileOrder, solutionIds := getChapterFourFileOrder()
+	// addPreNextLabel(chapterFourFileOrder, chapterThreeFileOrder, solutionIds, "ChapterThree", "ChapterFour", "")
 }
 
 func addPreNextLabel(order, preOrder []string, chapterFourIds []int, preChapter, chapter, nextChapter string) {

leetcode/0351.Android-Unlock-Patterns/351. Android Unlock Patterns.go

@@ -0,0 +1,41 @@
+package leetcode
+
+// blocker351[a][b] 记录从点 a 滑到点 b 必须先经过的中间点；0 表示两点相邻、无需经过中间点。
+// 例如 1->3 必须先经过 2，1->9 必须先经过 5。
+var blocker351 = [10][10]int{
+	1: {3: 2, 7: 4, 9: 5},
+	2: {8: 5},
+	3: {1: 2, 7: 5, 9: 6},
+	4: {6: 5},
+	6: {4: 5},
+	7: {1: 4, 3: 5, 9: 8},
+	8: {2: 5},
+	9: {1: 5, 3: 6, 7: 8},
+}
+
+// 解法一 回溯。0 号点是虚拟起点，从它出发可以到任意一个数字。
+func numberOfPatterns(m int, n int) int {
+	visited := make([]bool, 10)
+	return countPatterns351(visited, 0, 0, m, n)
+}
+
+// now 是当前所在的点，already 是已经选中的点数，统计长度落在 [m,n] 内的合法图案数。
+func countPatterns351(visited []bool, now, already, m, n int) int {
+	res := 0
+	if already >= m && already <= n {
+		res++
+	}
+	if already >= n { // 已达到最大长度，无需再往下选
+		return res
+	}
+	for next := 1; next <= 9; next++ {
+		mid := blocker351[now][next]
+		// next 没被用过，且 next 与 now 相邻（mid==0）或中间点已被划过（visited[mid]）
+		if !visited[next] && (mid == 0 || visited[mid]) {
+			visited[next] = true
+			res += countPatterns351(visited, next, already+1, m, n)
+			visited[next] = false
+		}
+	}
+	return res
+}

leetcode/0351.Android-Unlock-Patterns/351. Android Unlock Patterns_test.go

@@ -0,0 +1,67 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question351 struct {
+	para351
+	ans351
+}
+
+// para is the parameter
+// one represents the first parameter, two the second
+type para351 struct {
+	one int
+	two int
+}
+
+// ans is the answer
+// one represents the first answer
+type ans351 struct {
+	one int
+}
+
+func Test_Problem351(t *testing.T) {
+
+	qs := []question351{
+
+		{
+			para351{1, 1},
+			ans351{9},
+		},
+
+		{
+			para351{1, 2},
+			ans351{65},
+		},
+
+		{
+			para351{2, 3},
+			ans351{376},
+		},
+
+		{
+			para351{4, 5},
+			ans351{8776},
+		},
+
+		{
+			para351{4, 9},
+			ans351{389112},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 351------------------------\n")
+
+	for _, q := range qs {
+		a, p := q.ans351, q.para351
+		got := numberOfPatterns(p.one, p.two)
+		fmt.Printf("【input】:%v       【output】:%v\n", p, got)
+		if got != a.one {
+			t.Fatalf("input m=%v n=%v: expected %v, got %v", p.one, p.two, a.one, got)
+		}
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/9990085.Maximal-Rectangle/85. Maximal Rectangle.go

@@ -1,5 +1,48 @@
 package leetcode
 
+// 解法一 逐行把矩阵看成柱状图，对每一行求“柱状图中最大矩形”（第 84 题）。
+// 时间复杂度 O(m*n)，空间复杂度 O(n)。
 func maximalRectangle(matrix [][]byte) int {
-	return 0
+	if len(matrix) == 0 || len(matrix[0]) == 0 {
+		return 0
+	}
+	n := len(matrix[0])
+	heights, res := make([]int, n), 0
+	for i := 0; i < len(matrix); i++ {
+		for j := 0; j < n; j++ {
+			if matrix[i][j] == '1' {
+				heights[j]++
+			} else {
+				heights[j] = 0
+			}
+		}
+		if area := largestRectangleArea85(heights); area > res {
+			res = area
+		}
+	}
+	return res
+}
+
+// 单调栈求柱状图中的最大矩形面积。
+func largestRectangleArea85(heights []int) int {
+	res, stack := 0, []int{}
+	for i := 0; i <= len(heights); i++ {
+		cur := 0
+		if i < len(heights) {
+			cur = heights[i]
+		}
+		for len(stack) > 0 && heights[stack[len(stack)-1]] >= cur {
+			top := stack[len(stack)-1]
+			stack = stack[:len(stack)-1]
+			width := i
+			if len(stack) > 0 {
+				width = i - stack[len(stack)-1] - 1
+			}
+			if area := heights[top] * width; area > res {
+				res = area
+			}
+		}
+		stack = append(stack, i)
+	}
+	return res
 }

leetcode/9990085.Maximal-Rectangle/85. Maximal Rectangle_test.go

@@ -30,13 +30,37 @@ func Test_Problem85(t *testing.T) {
 			para85{[][]byte{{'1', '0', '1', '0', '0'}, {'1', '0', '1', '1', '1'}, {'1', '1', '1', '1', '1'}, {'1', '0', '0', '1', '0'}}},
 			ans85{6},
 		},
+
+		{
+			para85{[][]byte{}},
+			ans85{0},
+		},
+
+		{
+			para85{[][]byte{{'0'}}},
+			ans85{0},
+		},
+
+		{
+			para85{[][]byte{{'1'}}},
+			ans85{1},
+		},
+
+		{
+			para85{[][]byte{{'1', '1'}, {'1', '1'}}},
+			ans85{4},
+		},
 	}
 
 	fmt.Printf("------------------------Leetcode Problem 85------------------------\n")
 
 	for _, q := range qs {
-		_, p := q.ans85, q.para85
-		fmt.Printf("【input】:%v       【output】:%v\n", p, maximalRectangle(p.one))
+		a, p := q.ans85, q.para85
+		got := maximalRectangle(p.one)
+		fmt.Printf("【input】:%v       【output】:%v\n", p, got)
+		if got != a.one {
+			t.Fatalf("input %v: expected %v, got %v", p.one, a.one, got)
+		}
 	}
 	fmt.Printf("\n\n\n")
 }

leetcode/9990316.Remove-Duplicate-Letters/316. Remove Duplicate Letters.go

@@ -1,5 +1,27 @@
 package leetcode
 
+// 解法一 贪心 + 单调栈。每个字母只保留一个，结果在所有可行解中字典序最小。
+// 用 last 记录每个字母最后出现的下标；遍历时若当前字符比栈顶小，且栈顶字符后面还会
+// 再出现，就把栈顶弹出，从而让结果尽量小。时间复杂度 O(n)，空间复杂度 O(1)（26 个字母）。
 func removeDuplicateLetters(s string) string {
-	return ""
+	var last [26]int
+	for i := 0; i < len(s); i++ {
+		last[s[i]-'a'] = i
+	}
+	var inStack [26]bool
+	stack := []byte{}
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if inStack[c-'a'] {
+			continue
+		}
+		for len(stack) > 0 && stack[len(stack)-1] > c && last[stack[len(stack)-1]-'a'] > i {
+			top := stack[len(stack)-1]
+			stack = stack[:len(stack)-1]
+			inStack[top-'a'] = false
+		}
+		stack = append(stack, c)
+		inStack[c-'a'] = true
+	}
+	return string(stack)
 }

leetcode/9990316.Remove-Duplicate-Letters/316. Remove Duplicate Letters_test.go

@@ -34,13 +34,25 @@ func Test_Problem316(t *testing.T) {
 			para316{"cbacdcbc"},
 			ans316{"acdb"},
 		},
+		{
+			para316{""},
+			ans316{""},
+		},
+		{
+			para316{"abcd"},
+			ans316{"abcd"},
+		},
 	}
 
 	fmt.Printf("------------------------Leetcode Problem 316------------------------\n")
 
 	for _, q := range qs {
-		_, p := q.ans316, q.para316
-		fmt.Printf("【input】:%v       【output】:%v\n", p, removeDuplicateLetters(p.one))
+		a, p := q.ans316, q.para316
+		got := removeDuplicateLetters(p.one)
+		fmt.Printf("【input】:%v       【output】:%v\n", p, got)
+		if got != a.one {
+			t.Fatalf("input %q: expected %q, got %q", p.one, a.one, got)
+		}
 	}
 	fmt.Printf("\n\n\n")
 }