记忆化搜索 HDU1032

#include <iostream>
#include<cstdio>
#include<cstring>


using namespace std;

int arr[7000001];

 int f(long long int i)
{
    if(i<=7000000)
    {
        if(arr[i]!=0)
            return arr[i];
        if(i%2==0)
            return arr[i]=f(i/2)+1;
        else
            return arr[i]=f(i*3+1)+1;
    }
    else
    {
        if(i%2==0)
            return f(i/2)+1;
        else
            return f(i*3+1)+1;
    }
}

int main()
{
    int m,n;
    memset(arr,0,sizeof(arr));
        arr[1]=1;
    while(scanf("%d%d",&m,&n)!=EOF)
    {
        int maxi=0;
         printf("%d %d ",m,n);
        if(m>n)
            swap(m,n);
        for(int i=m;i<=n;i++)
        {
            if(f(i)>maxi)
                maxi=arr[i];
        }
        printf("%d
",maxi);
    }
    return 0;
}