import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class Permutation {
public static void main(String[] args){
int nums[] = {
12,
2,
3,
9,
1,
15,
4,
20,
10,-
1};
boolean isUsed[] =
new boolean[nums.length];
List<Integer> result =
new ArrayList<Integer>();
List<List<Integer>> resultList =
new ArrayList<List<Integer>>();
Object[] aa = result.toArray();
recMergeSort(nums,
0, nums.length-
1);
}
public static void doPermute(
int[] nums,
boolean[] isUsed, List<Integer> result, List<List<Integer>> resultList){
if(result.size()==nums.length){
resultList.add(
new ArrayList<>(result));
return;
}
for(
int i =
0;i<nums.length;i++){
if(!isUsed[i]){
result.add(nums[i]);
isUsed[i] =
true;
doPermute(nums, isUsed, result, resultList);
result.remove(result.size()-
1);
isUsed[i] =
false;
}
}
}
static int j =
0;
public static void recMergeSort(
int[] arr,
int low,
int upper){
List<Integer> list =
new ArrayList<Integer>();
for(
int i =low;i<=upper;i++){
list.add(arr[i]);
}
System.out.println(
"sub array: "+(j++)+
" "+list);
if(low == upper){
return;
}
else{
int mid = (low + upper)/
2;
recMergeSort(arr, low, mid);
recMergeSort(arr, mid+
1, upper);
}
}
}
运行结果如下：
sub array:
0 [
12,
2,
3,
9,
1,
15,
4,
20,
10, -
1]
sub array:
1 [
12,
2,
3,
9,
1]
sub array:
2 [
12,
2,
3]
sub array:
3 [
12,
2]
sub array:
4 [
12]
sub array:
5 [
2]
sub array:
6 [
3]
sub array:
7 [
9,
1]
sub array:
8 [
9]
sub array:
9 [
1]
sub array:
10 [
15,
4,
20,
10, -
1]
sub array:
11 [
15,
4,
20]
sub array:
12 [
15,
4]
sub array:
13 [
15]
sub array:
14 [
4]
sub array:
15 [
20]
sub array:
16 [
10, -
1]
sub array:
17 [
10]
sub array:
18 [-
1]
