杭电1995

 1 //找规律即可，下附打表
 2 #include<stdio.h>
 3 int main()
 4 {
 5     int n;
 6     scanf("%d",&n);
 7     while(n--)
 8     {
 9         int a,b;
10         scanf("%d%d",&a,&b);
11         printf("%lld\n",(long long)1<<(a-b));
12     }
13 }

 1 //打表法
 2 #include<stdio.h>
 3 long long a[60];
 4 
 5 void cus(int x,long long y)
 6 {
 7     if(x>=60)
 8         return ;
 9     a[x]=y;
10     cus(x+1,y*2);
11 }
12 
13 int main()
14 {
15     cus(0,1);
16     int n;
17     scanf("%d",&n);
18     while(n--)
19     {
20         int b,c;
21         scanf("%d%d",&b,&c);
22         printf("%lld\n",a[b-c]);
23     }
24 }