仅使用加法,除法和乘法以固定数量的步长达到数字的算法
问题内容:
在工作中以及在游戏中的某一时刻进行游戏时,玩家会被投入奖励游戏中。他们需要赢取的金额是预先确定的,但是我们想提出一种算法,该算法使用加法,乘法和除法以x步的数量达到该金额。步骤的数量也将提前知道,因此算法只需要弄清楚如何使用该数量的步骤即可达到数量。
您只能使用+1到+ 15,x2,x4,/ 2,/
4。您可以在步骤中超出目标数目,但必须在最后一步中达到目标数目。步长通常在15到30之间,并且您始终从0开始。
例如:Amount:100,Steps:10 == + 10,+ 2,x2,+ 4,x4,+ 10,/ 2,+ 15,+ 15,+ 9
数量:40,步数:12 == +15,+1,+5,+2,+1,/ 2, 4,+6,+6,/ 4,+5, 2
我很好奇是否已经存在这样的东西?我确定我们可以提出一些建议,但是如果有通用的算法可以完成这项工作,我就不想重新发明轮子。
更新:对@FryGuy的代码进行了一些小的更改,使其到达随机到达目标编号所需的路线。他的解决方案按原样运作良好,但是在看到它可行并考虑@Argote和@Moron的评论之后,我意识到它需要具有一定的随机性,以使其吸引我们的玩家。在10个步骤中增加+1以达到10个目标效果很好,但是就我们的使用方式而言,这很“无聊”。非常感谢所有发表评论和回答的人。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace CR
{
class Program
{
static void Main(string[] args)
{
while (true)
{
int targetNumber = 20;
int steps = 13;
int[] route = null;
Boolean routeAcceptable = false;
// Continue choosing routes until we find one that is acceptable (doesn't average above or target win, but does exceed it at least once)
while(!routeAcceptable)
{
routeAcceptable = CalculateRoute(targetNumber, steps, out route) && route.Average() < targetNumber && route.Max() > targetNumber;
}
foreach (int i in route.Reverse())
{
Console.WriteLine(i);
}
Console.WriteLine("-----------------------");
Console.ReadLine();
}
}
static Boolean CalculateRoute(int targetNumber, int numSteps, out int[] route)
{
int maxValue = targetNumber * 16;
bool[,] reachable = new bool[numSteps + 1, maxValue];
// build up the map
reachable[0, 0] = true;
for (int step = 0; step < numSteps; step++)
{
for (int n = 0; n < maxValue; n++)
{
if (reachable[step, n])
{
foreach (int nextNum in ReachableNumbersFrom(n))
{
if (nextNum < maxValue && nextNum > 0)
{
reachable[step + 1, nextNum] = true;
}
}
}
}
}
// figure out how we got there
int[] routeTaken = new int[numSteps + 1];
int current = targetNumber;
for (int step = numSteps; step >= 0; step--)
{
routeTaken[step] = current;
bool good = false;
// Randomize the reachable numbers enumeration to make the route 'interesting'
foreach (int prev in RandomizedIEnumerbale(ReachableNumbersFromReverse(current)))
{
if (prev < targetNumber * 8)
{
if (reachable[step, prev])
{
current = prev;
good = true;
// Avoid hitting the same number twice, again to make the route 'interesting'
for (int c = numSteps; c >= 0; c--)
{
reachable[c, prev] = false;
}
break;
}
}
}
if (!good)
{
route = routeTaken;
return false;
}
}
route = routeTaken;
return true;
}
static IEnumerable<int> ReachableNumbersFrom(int n)
{
// additions
for (int i = 1; i <= 15; i++)
{
yield return n + i;
}
// mults/divides
yield return n / 2;
yield return n / 4;
yield return n * 2;
yield return n * 4;
}
static IEnumerable<int> ReachableNumbersFromReverse(int n)
{
// additions
for (int i = 1; i <= 15; i++)
{
if (n - i >= 0)
yield return n - i;
}
// mults/divides
if (n % 2 == 0)
yield return n / 2;
if (n % 4 == 0)
yield return n / 4;
yield return n * 2;
yield return n * 4;
}
static IEnumerable<int> RandomizedIEnumerbale(IEnumerable<int> enumerbale)
{
Random random = new Random(System.DateTime.Now.Millisecond);
return (
from r in
(
from num in enumerbale
select new { Num = num, Order = random.Next() }
)
orderby r.Order
select r.Num
);
}
}
}
问题答案:
我会使用动态编程。首先,建立一个地图,列出每个步骤可以到达的数字,然后回溯以找出如何到达那里:
void CalculateRoute(int targetNumber, int numSteps)
{
int maxValue = targetNumber * 16;
bool[,] reachable = new bool[numSteps + 1, maxValue];
// build up the map
reachable[0, 0] = true;
for (int step = 0; step < numSteps; step++)
{
for (int n = 0; n < maxValue; n++)
{
if (reachable[step, n])
{
foreach (int nextNum in ReachableNumbersFrom(n))
{
if (nextNum < maxValue && nextNum >= 0)
reachable[step + 1, nextNum] = true;
}
}
}
}
// figure out how we got there
int current = targetNumber;
for (int step = numSteps; step >= 0; step--)
{
Console.WriteLine(current);
bool good = false;
foreach (int prev in ReachableNumbersFromReverse(current))
{
if (reachable[step, prev])
{
current = prev;
good = true;
break;
}
}
if (!good)
{
Console.WriteLine("Unable to proceed");
break;
}
}
}
IEnumerable<int> ReachableNumbersFrom(int n)
{
// additions
for (int i = 1; i <= 15; i++)
yield return n + i;
// mults/divides
yield return n / 2;
yield return n / 4;
yield return n * 2;
yield return n * 4;
}
IEnumerable<int> ReachableNumbersFromReverse(int n)
{
// additions
for (int i = 1; i <= 15; i++)
yield return n - i;
// mults/divides
if (n % 2 == 0)
yield return n / 2;
if (n % 4 == 0)
yield return n / 4;
yield return n * 2;
yield return n * 4;
}