UVa 100 Problem: The 3n+1 problem (PC 110101)

solved:

#include <iostream>
#include <string>
#include <string.h>
#include <map>
#include <stdio.h>
#include <algorithm>
#include <queue>
#include <vector>
#include <math.h>
#include <set>
#define Max(a,b) ((a)>(b)?(a):(b))
#define Min(a,b) ((a)<(b)?(a):(b))
#define Max_N 1000000

typedef long long LL;

using namespace std;

int dp[Max_N];
int CalLen(LL n);
int solve(int down,int up)
{
    int L = Min(down , up);
    int R = Max(down , up);
    int m = -1;
    for(int n = L;n <= R;n++)
    {
        m = Max(m , CalLen(n));
    }
    return m;
}

int CalLen(LL n)
{
    if(n == 1) return dp[n] = 1;
    n = n&1 ? n*3 + 1:n >> 1;
    if(n < Max_N)
    {
        if(dp[n] == -1)
        {
            dp[n] = CalLen(n);
        }
        return 1 + dp[n];
    }
    return 1 + CalLen(n);
}

int main()
{
    int down , up;
    memset(dp , -1 , sizeof(dp));
    while(scanf("%d%d",&down,&up) != EOF)
    {
        printf("%d %d %d\n",down,up,solve(down,up));
    }
    return 0;
}