fix online code-exercise issue, and optimize readme

Sunrisepeak · Sunrisepeak · commit 98aaec799d01 · 2026-03-16T07:11:05.000+08:00
diff --git a/.devcontainer/postCreate.sh b/.devcontainer/postCreate.sh
@@ -9,4 +9,10 @@ if ! command -v xlings >/dev/null 2>&1; then
   curl -fsSL https://d2learn.org/xlings-install.sh | bash
 fi
 
-echo "xlings installed"
+echo "xlings installed"
+
+echo "Installing dependencies (d2x) by xlings..."
+
+xlings install --verbose
+
+echo "Dependencies installed"
diff --git a/README.md b/README.md
@@ -67,6 +67,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker
diff --git a/README.zh.hant.md b/README.zh.hant.md
@@ -67,6 +67,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker
diff --git a/README.zh.md b/README.zh.md
@@ -67,6 +67,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker
diff --git a/book/en/src/README.md b/book/en/src/README.md
@@ -63,6 +63,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker
diff --git a/book/src/README.md b/book/src/README.md
@@ -63,6 +63,7 @@ irm https://d2learn.org/xlings-install.ps1.txt | iex
 </details>
 
 ```bash
+xlings install d2x -y
 d2x install d2mcpp
 cd d2mcpp
 d2x checker
