cant-find-std-header-file-like-algorithm

If header file like this shows an error:

#include <algorithm>

Then check your clangd output in vscode panel. Clangd could have found a wrong compile_commands.json. In fact, clangd always trys to find a build/compile_commands.json from parent folder.

solution

You can copy a build/compile_commands.json into current workspace from some other directories.