(written questions) shuffle algorithm

Topic:

Given n cards and a random function, design a shuffle algorithm

Ideas:

Assuming that array A is the number represented by poker, the process of shuffling is the process of exchanging elements in the array.

Shuffling is a random process and a combination of permutations.

Assuming there are n cards, the possible arrangement of the combinations is n! =n* (N-1) *....*2*1.

There are two kinds of random shuffle functions:

1, A[i]=a[rand ()%N]

2, A[i]=a[rand ()% (n-i)]

But in the first case, the choice may be n^n, and the second case is N!

So the second stochastic algorithm is more consistent.

Code:

void Shuffle (int a[],int len) {int val,tmp;for (int i=0;i<len;i++) {Val=i+rand ()% (len-i); tmp=a[i];a[i]=a[val];a[val ]=tmp;}}

(written questions) shuffle algorithm