2012-01-23 78 views
3

关于一座100层高的建筑物和两个玻璃球,有一种流行的puzzle。我看到了解决方案,现在我想知道我是否可以通过编程的方式解决难题如何以编程方式解决2玻璃球难题?

微不足道的编程解决方案是一个完整的搜索(我相信我可以使用回溯代码)。有没有更好的编程解决方案?我可以使用动态编程来解决这个难题吗?

+4

你有没有试过,或者你只是想让我们做到这一点? ;) – annonymously

+0

您可以将您的问题标记为**作业** – Arung

+4

http://en.wikipedia.org/wiki/Dynamic_programming#Egg_dropping_puzzle – jgroenen

回答

5

这与卵滴拼图类似。我会给你在动态编程的基本策略。将此与您的问题紧密联系起来。

# include <stdio.h> 
# include <limits.h> 

// A utility function to get maximum of two integers 
int max(int a, int b) { return (a > b)? a: b; } 

/* Function to get minimum number of trails needed in worst 
case with n eggs and k floors */ 
int eggDrop(int n, int k) 
{ 
/* A 2D table where entery eggFloor[i][j] will represent minimum 
    number of trials needed for i eggs and j floors. */ 
int eggFloor[n+1][k+1]; 
int res; 
int i, j, x; 

// We need one trial for one floor and0 trials for 0 floors 
for (i = 1; i <= n; i++) 
{ 
    eggFloor[i][1] = 1; 
    eggFloor[i][0] = 0; 
} 

// We always need j trials for one egg and j floors. 
for (j = 1; j <= k; j++) 
    eggFloor[1][j] = j; 

// Fill rest of the entries in table using optimal substructure 
// property 
for (i = 2; i <= n; i++) 
{ 
    for (j = 2; j <= k; j++) 
    { 
     eggFloor[i][j] = INT_MAX; 
     for (x = 1; x <= j; x++) 
     { 
      res = 1 + max(eggFloor[i-1][x-1], eggFloor[i][j-x]); 
      if (res < eggFloor[i][j]) 
       eggFloor[i][j] = res; 
     } 
    } 
} 

// eggFloor[n][k] holds the result 
return eggFloor[n][k]; 
} 

/* Driver program to test to pront printDups*/ 
int main() 
{ 
    int n = 2, k = 36; 
    printf ("\nMinimum number of trials in worst case with %d eggs and %d floors is %d \n", n, k, eggDrop(n, k)); 
    return 0; 
} 

输出: 在最坏的情况下试验的最小数量与2个鸡蛋和36层为8

+0

没有冒犯,但这不是最好的解决方案。最简单的情况是直到鸡蛋休息时跳过N的sqrt。一旦鸡蛋破碎,用N的sqrt备份并线性搜索。 N的时间复杂度sqrt并且没有表格。这很简单。 – Michael

0

我很抱歉,但以前的答案只是不能妥善处理这个问题。最好的时间是N的sqrt。有人会试图用logn来反驳这一点,但我很抱歉,其实并非如此。

// my prentend breaking function 
function itBreaks(level) { 
    return level > 36; 
} 

function search(maxLevel) { 
    var sqrtN = Math.floor(Math.sqrt(maxLevel)); 
    var i = 0; 
    for (;i < maxLevel; i += sqrtN) { 
     if (itBreaks(i)) { 
      break; 
     } 
    } 

    for (i -= sqrtN; i < maxLevel; i++) { 
     if (itBreaks(i)) { 
      return i - 1; 
     } 
    } 
}