【LintCode】数组的全排序(1)

public class Solution{
private static void print(char[] arr){
if(arr == null || arr.length == 0){
return;
}
for(int i = 0; i < arr.length; i++){
System.out.print(arr[i]);
}
System.out.println();
}
private static void swap(char[] ch, int i, int k){
char temp = ch[i];
ch[i] = ch[k];
ch[k] = temp;
}
private static void permutation(char[] arr, int k){
//递归：f(n) = k·f(n-1),将字符串中每一个元素都放到第k位（假设就是首位，即k设为0），剩下的n-1个进行全排列(递归)
// (k
4000
<= arr.length-1)

if(k == arr.length - 1){
print(arr);
return;
}
for(int i = k; i < arr.length; i++) {
swap(arr,i,k);
permutation(arr,k+1);
swap(arr,i,k);
}
}

public static void main(String[] args){
char[] ch = {'a','b','c'};
permutation(ch,0);
}
}