documentclass{beamer}
mode<presentation>
{
  usetheme{CambridgeUS}
  usecolortheme{dolphin}
  usecolortheme{rose}
  setbeamerfont*{title}{shape=itshape, family=rmfamily}
  setbeamercovered{transparent}
}
usepackage{algorithm2e}

begin{document}
begin{frame}{Hello world}
  begin{center}
    begin{minipage}{0.8linewidth}
    %scalebox{0.8}{
      begin{algorithm}[H]
    DontPrintSemicolon
    KwSty{type} brow : KwSty{int}$[M+1]$;
    KwSty{type} bcol : KwSty{int}$[N+1]$;
    KwSty{type} val : KwSty{real}$[k]$;
    KwSty{type} val_ptr : KwSty{int}$[K+1]$;
    KwSty{type} ind : KwSty{int}$[K]$;
    KwSty{type} ptr : KwSty{int}$[M+1]$;
    everypar={nl}
    ForEach{block row $I$}{
      $i_0 leftarrow brow[I]$;
      $r leftarrow brow[I+1]$;
      Let $hat{y} leftarrow y_{i_0:(i_0+r-1)}$;
      For{$b=ptr[I] KwTo ptr[I+1]$}{
        $J leftarrow ind[b]$;
        $j_0 leftarrow bcol[J]$;
        $c leftarrow bcol[J+1]-bcol[J]$;
        Let $hat{x} leftarrow x_{j_0:(j_0+c-1)}$;
        Let $hat{A} leftarrow a_{i_0:(i_0+r-1),j_0:(j_0+c-1)}$;
        Perform $r times c$ block multiply, $hat{y} leftarrow hat{y}+hat{A} cdot hat{x}$;
      }
    }
      end{algorithm}
      %}
    end{minipage}
  end{center}

end{frame}
end{document}

documentclass{beamer}
mode<presentation>
{
  usetheme{CambridgeUS}
  usecolortheme{dolphin}
  usecolortheme{rose}
  setbeamerfont*{title}{shape=itshape, family=rmfamily}
  setbeamercovered{transparent}
}
usepackage{algorithm2e}

begin{document}
begin{frame}{Hello world}
  begin{center}
    scalebox{0.75}{
    begin{minipage}{0.7linewidth}
      begin{algorithm}[H]
    DontPrintSemicolon
    KwSty{type} brow : KwSty{int}$[M+1]$;
    KwSty{type} bcol : KwSty{int}$[N+1]$;
    KwSty{type} val : KwSty{real}$[k]$;
    KwSty{type} val_ptr : KwSty{int}$[K+1]$;
    KwSty{type} ind : KwSty{int}$[K]$;
    KwSty{type} ptr : KwSty{int}$[M+1]$;
    everypar={nl}
    ForEach{block row $I$}{
      $i_0 leftarrow brow[I]$;
      $r leftarrow brow[I+1]$;
      Let $hat{y} leftarrow y_{i_0:(i_0+r-1)}$;
      For{$b=ptr[I] KwTo ptr[I+1]$}{
        $J leftarrow ind[b]$;
        $j_0 leftarrow bcol[J]$;
        $c leftarrow bcol[J+1]-bcol[J]$;
        Let $hat{x} leftarrow x_{j_0:(j_0+c-1)}$;
        Let $hat{A} leftarrow a_{i_0:(i_0+r-1),j_0:(j_0+c-1)}$;
        Perform $r times c$ block multiply, $hat{y} leftarrow hat{y}+hat{A} cdot hat{x}$;
      }
    }
      end{algorithm}
    end{minipage}%
    }
  end{center}

end{frame}
end{document}

documentclass{beamer}
mode<presentation>
{
  usetheme{CambridgeUS}
  usecolortheme{dolphin}
  usecolortheme{rose}
  setbeamerfont*{title}{shape=itshape, family=rmfamily}
  setbeamercovered{transparent}
}
usepackage{algorithm2e}

begin{document}


begin{frame}{Hello world}
  begin{center}
    begin{minipage}{0.8linewidth}
        scriptsize
      begin{algorithm}[H]
    DontPrintSemicolon
    KwSty{type} brow : KwSty{int}$[M+1]$;
    KwSty{type} bcol : KwSty{int}$[N+1]$;
    KwSty{type} val : KwSty{real}$[k]$;
    KwSty{type} val_ptr : KwSty{int}$[K+1]$;
    KwSty{type} ind : KwSty{int}$[K]$;
    KwSty{type} ptr : KwSty{int}$[M+1]$;
    everypar={nl}
    ForEach{block row $I$}{
      $i_0 leftarrow brow[I]$;
      $r leftarrow brow[I+1]$;
      Let $hat{y} leftarrow y_{i_0:(i_0+r-1)}$;
      For{$b=ptr[I] KwTo ptr[I+1]$}{
        $J leftarrow ind[b]$;
        $j_0 leftarrow bcol[J]$;
        $c leftarrow bcol[J+1]-bcol[J]$;
        Let $hat{x} leftarrow x_{j_0:(j_0+c-1)}$;
        Let $hat{A} leftarrow a_{i_0:(i_0+r-1),j_0:(j_0+c-1)}$;
        Perform $r times c$ block multiply, $hat{y} leftarrow hat{y}+hat{A} cdot hat{x}$;
      }
    }
      end{algorithm}
    end{minipage}
  end{center}
end{frame}

end{document}

documentclass{beamer}
mode<presentation>
{
  usetheme{CambridgeUS}
  usecolortheme{dolphin}
  usecolortheme{rose}
  setbeamerfont*{title}{shape=itshape, family=rmfamily}
  setbeamercovered{transparent}
}
usepackage{algorithm2e}

begin{document}

% This solution is evil!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
% use it at your own risk!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
begin{frame}[shrink]{Hello world}
  begin{center}
    begin{minipage}{0.8linewidth}
      begin{algorithm}[H]
    DontPrintSemicolon
    KwSty{type} brow : KwSty{int}$[M+1]$;
    KwSty{type} bcol : KwSty{int}$[N+1]$;
    KwSty{type} val : KwSty{real}$[k]$;
    KwSty{type} val_ptr : KwSty{int}$[K+1]$;
    KwSty{type} ind : KwSty{int}$[K]$;
    KwSty{type} ptr : KwSty{int}$[M+1]$;
    everypar={nl}
    ForEach{block row $I$}{
      $i_0 leftarrow brow[I]$;
      $r leftarrow brow[I+1]$;
      Let $hat{y} leftarrow y_{i_0:(i_0+r-1)}$;
      For{$b=ptr[I] KwTo ptr[I+1]$}{
        $J leftarrow ind[b]$;
        $j_0 leftarrow bcol[J]$;
        $c leftarrow bcol[J+1]-bcol[J]$;
        Let $hat{x} leftarrow x_{j_0:(j_0+c-1)}$;
        Let $hat{A} leftarrow a_{i_0:(i_0+r-1),j_0:(j_0+c-1)}$;
        Perform $r times c$ block multiply, $hat{y} leftarrow hat{y}+hat{A} cdot hat{x}$;
      }
    }
      end{algorithm}
    end{minipage}
  end{center}
end{frame}



end{document}