问题123: 变量交换

//1

#include <stdio.h>
int main()
{
int a,b,t;
scanf("%d%d",&a,&b);
t=a;
a=b;
b=t;
printf("%d %d",a,b);
}
//2
#include <stdio.h>
int main()
{
  int a,b;
  scanf("%d%d",&a,&b);
  a=a+b;
  b=a-b;
  a=a-b;
  printf("%d%d",a,b);
}

//3
#include <stdio.h>
int main()
{
int a,b;
scanf("%d%d",&a,&b);