HDU 1165 Eddy's research II (推公式)

Eddy's research II

Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 3122 Accepted Submission(s): 1137


[align=left]Problem Description[/align]
As is known, Ackermann function plays an important role in the sphere of theoretical computer science. However, in the other hand, the dramatic fast increasing pace of the function caused the value of Ackermann function hard to calcuate.

Ackermann function can be defined recursively as follows:

#include<cstdio>
#include<cstring>
#include<stdlib.h>
#include<algorithm>
using namespace std;
__int64 A(int m,int n)
{
if(m==0)  return n+1;
if(m==1)  return n+2;
if(m==2)  return 2*n+3;
if(m==3)  return (1<<(n+3))-3;
}
int main()
{
int m,n;
while(scanf("%d %d",&m,&n)!=EOF)
{
printf("%I64d\n",A(m,n));
}
return 0;
}

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