shrink space tricks in latex (algorithm, equation and itemize)
Before and after algorithms:

\setlength{\textfloatsep}{0.1cm}
\setlength{\floatsep}{0.1cm}

Before and after equations:

\usepackage{amsmath}
\makeatletter
\[email protected]@macro\normalsize{%
\setlength\abovedisplayskip{-6pt}
\setlength\belowdisplayskip{0pt}
\setlength\abovedisplayshortskip{-6pt}
\setlength\belowdisplayshortskip{0pt}
}
\makeatother

Before and after itemize:

\usepackage{enumitem}
\setlist{nolistsep}