【代码】LCA转成RMQ后的ST算法

program Xiong;
uses
        math;
type
        rec=record
            a,b:longint;
        end;
var
        n,m,i,t,s,a,b,j,q,k:longint;
        oula,dep,app,list,next:array[0..100]of longint;
        side:array[0..100]of rec;
        f:array[0..100,0..100]of longint;

procedure make(a,b:longint);
var
        k:longint;
begin
        inc(s);
        side[s].a:=a;
        side[s].b:=b;
        if list[a]=0 then
            list[a]:=s
        else begin
            k:=list[a];
            next[s]:=k;
            list[a]:=s;
        end;
end;

procedure all(i,d:longint);
var
        k:longint;
begin
        inc(t);
        oula[t]:=i;
        app[i]:=t;
        dep[i]:=d;
        k:=list[i];
        while k<>0 do begin
            all(side[k].b,d+1);
            inc(t);
            oula[t]:=i;
            k:=next[k];
        end;
end;

function min(a,b:longint):longint;
begin
        if dep[a]<dep[b] then exit(a) else exit(b);
end;

begin
        assign(input,'input.txt');reset(input);
        assign(output,'output.txt');rewrite(output);

        read(n,m);
        for i:=1 to m do begin
            read(a,b);
            make(a,b);
        end;

        all(1,1);

        for i:=1 to t do
            f[i,0]:=oula[i];
        for j:=1 to trunc(ln(t)/ln(2)) do
            for i:=1 to t do
                f[i,j]:=min(f[i,j-1],f[i+2**(j-1),j-1]);

        read(q);
        for i:=1 to q do begin
            read(a,b);
            if app[a]>app[b] then begin
                k:=a;
                a:=b;
                b:=k;
            end;
            k:=trunc(ln(app[b]-app[a]+1)/ln(2));
            writeln(min(f[app[a],k],f[app[b]-2**k+1,k]));
        end;

        close(input);
        close(output);
end.

今天才写的ST算法……一直感觉自己缩进很漂亮的样子。