m*******a
发帖数: 83 | 1 从10个不同的球中任意取5个球。算法如何实现呢？ |
q*****g
发帖数: 72 | 2 permutation. take first 5
【在 m*******a 的大作中提到】
: 从10个不同的球中任意取5个球。算法如何实现呢？
|
m*******a
发帖数: 83 | 3 具体算法如何实现呢？ 任何语言都可以
【在 q*****g 的大作中提到】
: permutation. take first 5
|
q*****g
发帖数: 72 | 4 for (int i = 1; i <= 10; +=i)
{
int j = rand() % (10-i+1) + i; // random number between i to 10
swap(a[i],a[j]);
}
// take first 5
【在 m*******a 的大作中提到】
: 具体算法如何实现呢？ 任何语言都可以
|
k****f
发帖数: 3794 | 5 你找找knuth的电子书，the art of computer programming volume 4
里面有一章就有详细介绍怎么产生排列组合的
【在 m*******a 的大作中提到】
: 具体算法如何实现呢？ 任何语言都可以
|
m*******a
发帖数: 83 | 6 能具体解释一下swap吗？
【在 q*****g 的大作中提到】
: for (int i = 1; i <= 10; +=i)
: {
: int j = rand() % (10-i+1) + i; // random number between i to 10
: swap(a[i],a[j]);
: }
: // take first 5
|
q*****g
发帖数: 72 | 7 void swap(int i, int j)
{
int temp;
temp = i;
i = j;
j = temp;
}
【在 m*******a 的大作中提到】
: 能具体解释一下swap吗？
|
m*******a
发帖数: 83 | 8 I see, but if I take the first 5 of the randon arrangement, how to avoid the
repeated ones?
【在 q*****g 的大作中提到】
: void swap(int i, int j)
: {
: int temp;
: temp = i;
: i = j;
: j = temp;
: }
|
k****f
发帖数: 3794 | 9 google就有了
http://www.merriampark.com/comb.htm
the
【在 m*******a 的大作中提到】
: I see, but if I take the first 5 of the randon arrangement, how to avoid the
: repeated ones?
|
O******e
发帖数: 734 | 10
The above line is strictly speaking problematic unless you can guarantee
that the low-order bits returned by rand() are uniformly randomized.
See either Chapter 3 of Knuth or Chapter 7 of Numerical Recipes or
"man -S 3 rand" on a Linux system for the correct way of randomly
selecting integers with uniform probability.
【在 q*****g 的大作中提到】
: for (int i = 1; i <= 10; +=i)
: {
: int j = rand() % (10-i+1) + i; // random number between i to 10
: swap(a[i],a[j]);
: }
: // take first 5
|
a*********e
发帖数: 697 | 11 agree, set random seed first.
【在 O******e 的大作中提到】
:
: The above line is strictly speaking problematic unless you can guarantee
: that the low-order bits returned by rand() are uniformly randomized.
: See either Chapter 3 of Knuth or Chapter 7 of Numerical Recipes or
: "man -S 3 rand" on a Linux system for the correct way of randomly
: selecting integers with uniform probability.
|
