[POJ1207]The 3n+1 Problem

题目：The 3n+1 Problem

水题，练手

但是会有一些题目没给出的信息，容易找不出bug

1、输入的i，j没有顺序，需要先排序

2、输出的i，j需要按原顺序输出

#include<iostream>
using namespace std;

int ans[100000000]; //all value is 0

int compute(int n)
{
    if (ans[n] != 0)   return ans[n];
    if (n % 2 == 1)
    {
        ans[n] = compute(3 * n + 1) + 1;
    }
    else
    {
        ans[n] = compute(n / 2) + 1;
    }
    return ans[n];
}

int max(int i, int j)
{
    int mx = 0;
    int iter = i;
    while (iter <= j)
    {
        if (mx < ans[iter])
            mx = ans[iter];
        iter++;
    }
    return mx;
}

int main()
{
    ans[1] = 1;

    int i, j, x, y; //x,y is used to output
    while (cin >> i >> j)
    {
        x = i, y = j;

        if (i > j)
        {
            int t = i;
            i = j;
            j = t;
        }

        int iter = i;
        while (iter <= j)
        {
            compute(iter);
            iter++;
        }

        cout << x << " " << y << " " << max(i, j) << endl;
    }
    return 0;
}