$\,\qquad$

diff --git a/docs/intro/htc.md b/docs/intro/htc.md
index 619aa1a..f2aba58 100644 (file)
--- a/docs/intro/htc.md
+++ b/docs/intro/htc.md
@@ -159,7 +159,11 @@ LaTeX 作为公式排版的首选，我们应当正确地使用它。因此对
 
 伪码具体格式没有严格要求，请参考算法导论或学术论文。注意不要写成 Python，赋值使用 `$\gets$` 表示。
 
-在 Wiki 中，使用 Markdown 引用来书写伪代码，使用 `$\qquad$` 表示缩进。
+在 Wiki 中，使用 Markdown 引用来书写伪代码。
+
+不缩进：`> $\,$ your codes`。
+
+两层缩进：`> $\,\qquad\qquad$ $x\gets 0$`。
 
 例如：
 
@@ -169,40 +173,40 @@ LaTeX 作为公式排版的首选，我们应当正确地使用它。因此对
 >
 >  **Method.** 
 >
->  $result \gets \varnothing$ 
+>  $\,$ $result \gets \varnothing$ 
 >
-> sort $e$ into nondecreasing order by weight $w$ 
+>  $\,$ sort $e$ into nondecreasing order by weight $w$ 
 >
->  **for** each $(u, v, w)$ in the sorted $e$ 
+>  $\,$ **for** each $(u, v, w)$ in the sorted $e$ 
 >
->  $\qquad$  **if**  $u$ and $v$ are not connected in the union-find set
+>  $\,\qquad$  **if**  $u$ and $v$ are not connected in the union-find set
 >
->  $\qquad\qquad$ connect $u$ and $v$ in the union-find set
+>  $\,\qquad\qquad$ connect $u$ and $v$ in the union-find set
 >
->  $\qquad\qquad result \gets result\ \bigcup\ \{(u, v, w)\}$ 
+>  $\,\qquad\qquad$ $result \gets result\ \bigcup\ \{(u, v, w)\}$ 
 >
->  **return**  $result$ 
+>  $\,$ **return**  $result$ 
 
 ```markdown
-> **Input.** The edges of the graph $e$, where each element in $e$ is $(u, v, w)$ denoting that there is an edge between $u$ and $v$ weighted $w$.
+>  **Input.** The edges of the graph $e$ , where each element in $e$ is $(u, v, w)$ denoting that there is an edge between $u$ and $v$ weighted $w$ .
 >
-> **Output.** The edges of the MST of the input graph.
+>  **Output.** The edges of the MST of the input graph.
 >
-> **Method.**
+>  **Method.** 
 >
-> $result \gets \varnothing$
+>  $\,$ $result \gets \varnothing$ 
 >
-> sort $e$ into nondecreasing order by weight $w$
+>  $\,$ sort $e$ into nondecreasing order by weight $w$ 
 >
-> **for** each $(u, v, w)$ in the sorted $e$
+>  $\,$ **for** each $(u, v, w)$ in the sorted $e$ 
 >
-> $\qquad$**if** $u$ and $v$ are not connected in the union-find set
+>  $\,\qquad$  **if**  $u$ and $v$ are not connected in the union-find set
 >
-> $\qquad\qquad$connect $u$ and $v$ in the union-find set
+>  $\,\qquad\qquad$ connect $u$ and $v$ in the union-find set
 >
-> $\qquad\qquad result \gets result\ \bigcup\ \{(u, v, w)\}$
+>  $\,\qquad\qquad$ $result \gets result\ \bigcup\ \{(u, v, w)\}$ 
 >
-> **return** $result$
+>  $\,$ **return**  $result$ 
 ```
 
 ## 图解