程序打印特定元素的排列 [英] Program to print permutations of given elements

问题描述

我最近在ACM认证的编程竞赛的一部分。这是一个我不能这样做在当时的问题是：

I recently took part in ACM certified programming competition. This is the question which I could not do at that time:

由于有n个元素整数数组，编写一个程序来打印所有的排列组合。

"Given an array of integers having n elements, write a program to print all the permutations."

请告诉我该怎么做这个问题。是否有任何的算法来做这样的问题吗？

Please tell me how to do this question. Is there any algorithm to do this kind of questions?

推荐答案

假设没有重复：只要改变每个元素与所有可能的下列元素，并递归调用函数

assuming there are no repeats: just change each element with all possible following elements, and recursively invoke the function.

void permute(int *array,int i,int length) { 
  if (length == i){
     printArray(array,length);
     return;
  }
  int j = i;
  for (j = i; j < length; j++) { 
     swap(array+i,array+j);
     permute(array,i+1,length);
     swap(array+i,array+j);
  }
  return;
}

您可以看到code与辅助的功能交换（）和 printArray（）执行与一基本的测试案例在 ideone

You can see the code with auxilary functions swap() and printArray() performing with a basic test case at ideone

奖金：这是类似于费雪耶茨洗牌的想法< /一>，但在这里 - 这一翻译到我与随机选择的下一个元素 - 你与他们交换了它 - 每一次

Bonus: This is similar to the idea of fisher-yates shuffle, but in here - intead to swapping the element at i with randomly chosen following element - you swap it with all of them - each at a time.

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