洛谷P1303 A*B Problem

题目

求两数的积。

题解

高精度乘法

代码

var
  n,i,j:longint;
  s1,s2:ansistring;
  a,b,c:array[1..100000]of longint;

procedure mub;
var
  i,j,x:longint;
begin
  for i:=1 to length(s1) do
    begin
      x:=0;
      for j:=1 to length(s2) do
        begin
          c[i+j-1]:=a[i]*b[j]+x+c[i+j-1];
          x:=c[i+j-1] div 10;
          c[i+j-1]:=c[i+j-1] mod 10;
        end;
      c[i+j]:=x;
    end;
end;

begin
  readln(s1);
  readln(s2);
  for i:=1 to length(s1) do
    a[length(s1)-i+1]:=ord(s1[i])-ord('0');
  for i:=1 to length(s2) do
    b[length(s2)-i+1]:=ord(s2[i])-ord('0');
  mub;
  i:=100000;
  while (c[i]=0)and(i>1) do dec(i);
  for j:=i downto 1 do
    write(c[j]);
end.