BÀI TẬP LẬP TRÌNH - CODE THUẬT TOÁN KRUSKAL

CONST MAXV=100;MAXE=(MAXV-1)*MAXV DIV 2;
TYPE CANH=RECORD
U,V,C:INTEGER;
MARK:BOOLEAN;
END;
VAR E:ARRAY[1..MAXE]OF CANH;
LAB:ARRAY[1..MAXV]OF INTEGER;
M,N:INTEGER;CONNECTED:BOOLEAN;F1,F2:TEXT;
{==========================================================
==========}
PROCEDURE NHAP;
VAR I:INTEGER;
BEGIN
READLN(F1,N,M);
FOR I:=1 TO M DO WITH E[I] DO READLN(F1,U,V,C);
END;
{==========================================================
==========}
PROCEDURE TAORONG;
VAR I:INTEGER;
BEGIN
FOR I:=1 TO N DO LAB[I]:=-1;
FOR I:=1 TO M DO E[I].MARK:=FALSE;
END;
{==========================================================
==========}
FUNCTION GETROOT(V:INTEGER):INTEGER;{LAY GOC CUA CAY
CHUA V}
BEGIN
WHILE LAB[V]>0 DO V:=LAB[V];
GETROOT:=V;

END;
{==========================================================
==========}
PROCEDURE UNION(R1,R2:INTEGER);
VAR X:INTEGER;
BEGIN
X:=LAB[R1]+LAB[R2];
IF LAB[R1]>LAB[R2] THEN
BEGIN
LAB[R1]:=R2;
LAB[R2]:=X;
END
ELSE
BEGIN
LAB[R1]:=X;
LAB[R2]:=R1;
END;
END;
{==========================================================
==========}
PROCEDURE AH(ROOT,LAST:INTEGER);
VAR KEY:CANH;CON:INTEGER;
BEGIN
KEY:=E[ROOT];
WHILE ROOT*2<=LAST DO
BEGIN
CON:=ROOT*2;
IF (CON<LAST)AND(E[CON+1].C<E[CON].C) THEN INC(CON);
IF KEY.C<=E[CON].C THEN BREAK;
E[ROOT]:=E[CON];

ROOT:=CON;
END;
E[ROOT]:=KEY;
END;
{==========================================================
==========}
PROCEDURE KRUSKAL;
VAR I,R1,R2,COUNT,A:INTEGER;TMP:CANH;
BEGIN
COUNT:=0;
CONNECTED:=FALSE;
FOR I:=M DIV 2 DOWNTO 1 DO AH(I,M);
FOR I:=M-1 DOWNTO 1 DO
BEGIN
TMP:=E[1];E[1]:=E[I+1];E[I+1]:=TMP;AH(1,I);
R1:=GETROOT(E[I+1].U);R2:=GETROOT(E[I+1].V);
IF R1<>R2 THEN
BEGIN
E[I+1].MARK:=TRUE;
INC(COUNT);
IF COUNT=N-1 THEN
BEGIN
CONNECTED:=TRUE;EXIT;
END;
UNION(R1,R2);
END;
END;
END;
{==========================================================
==========}

PROCEDURE XUAT;
VAR I,COUNT,W:INTEGER;
BEGIN
IF NOT CONNECTED THEN WRITELN(F2,'DO THI KHONG LIEN
THONG')
ELSE
BEGIN
WRITELN(F2,'CAY KHUNG NHO NHAT LA:');
COUNT:=0;W:=0;
FOR I:=1 TO M DO WITH E[I] DO
BEGIN
IF MARK THEN
BEGIN
WRITELN(F2,'(',U,',',V,')=',C);
INC(COUNT);
W:=W+C;
END;
IF COUNT=N-1 THEN BREAK;
END;
WRITELN(F2,'TONG =',W);
END;
END;
{==========================================================
==========}
BEGIN