当时看到这个题只想到了分解质因数和判断什么时候输出-1，忘记输出的时候打乱他们的顺序了。
思路：
第一步：找出当前数的所有质因数和他们出现的次数，我将他们放入了一个存储long[]类型的Arraylist中。
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| List<long[]> list = new ArrayList<>();
for(long i = 2L; i <= x / i ; i++) {
int nums = 0;
while (x % i == 0) {
x = x / i;
nums++;
}
if(nums != 0) {
list.add(new long[]{i, nums});
}
}
if(x > 1) list.add(new long[]{x, 1});
|
第二步：排序判断-1的情况，因为当最大的数中间的间隙不能被填满，那么两个数就相邻，输出-1
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| long sum = 0;
for (long[] longs : list) {
sum += longs[1];
}
list.sort(Comparator.comparing(o -> (-o[1])));
long val = list.get(0)[0];
long max = list.get(0)[1];
list.remove(0);
if(sum - max < max - 1) {
System.out.println(-1);
return;
}
|
第三步：将出现次数最多的质数分成若干份，每份依次插入到后面的质数中间，除了第一份和出现次数第二多的质数多1，剩下的依次和出现其他次数的质数的数量相等，知道出现次数最多的质数被分完。然后依次输出遍历质因数，每输出一次将该质因数的个数减一。
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| if(list.size() >= 1) {
long temp = list.get(0)[1];
if(temp < max) {
list.add(0, new long[]{val, temp + 1});
max = max - temp - 1;
}else{
list.add(0, new long[]{val, temp});
max = max - temp;
}
}
for(int i = 2; ; i = i + 2) {
if(i >= list.size() || max <= 0) {
break;
}
long temp = list.get(i)[1];
if(max <= temp) {
list.add(i, new long[]{val, max});
max = 0;
break;
}
max -= temp;
list.add(i,new long[]{val, temp});
}
if(max != 0) list.add(new long[]{val, max});
n = list.size();
System.out.println(sum);
max = list.get(0)[1];
for(int i = 0; i < max; i++) {
for(int j = 0; j < n; j++) {
if(list.get(j)[1] != 0) {
bw.write(list.get(j)[0] + " ");
list.get(j)[1] = list.get(j)[1] - 1;
}
}
}
|
*AC代码：*
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| import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.*;
public class Main {
public static void main(String[] args) throws IOException {
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
Scanner scan = new Scanner(System.in);
long x = scan.nextLong();
if(x == 1) {
System.out.println(-1);
return;
}
Map<Long, Integer> map = new HashMap<>();
List<long[]> list = new ArrayList<>();
for(long i = 2L; i <= x / i ; i++) {
int nums = 0;
while (x % i == 0) {
x = x / i;
nums++;
}
if(nums != 0) {
list.add(new long[]{i, nums});
}
}
if(x > 1) list.add(new long[]{x, 1});
int n = list.size();
long sum = 0;
for (long[] longs : list) {
sum += longs[1];
}
list.sort(Comparator.comparing(o -> (-o[1])));
long val = list.get(0)[0];
long max = list.get(0)[1];
list.remove(0);
if(sum - max < max - 1) {
System.out.println(-1);
return;
}
if(list.size() >= 1) {
long temp = list.get(0)[1];
if(temp < max) {
list.add(0, new long[]{val, temp + 1});
max = max - temp - 1;
}else{
list.add(0, new long[]{val, temp});
max = max - temp;
}
}
for(int i = 2; ; i = i + 2) {
if(i >= list.size() || max <= 0) {
break;
}
long temp = list.get(i)[1];
if(max <= temp) {
list.add(i, new long[]{val, max});
max = 0;
break;
}
max -= temp;
list.add(i,new long[]{val, temp});
}
if(max != 0) list.add(new long[]{val, max});
n = list.size();
System.out.println(sum);
max = list.get(0)[1];
for(int i = 0; i < max; i++) {
for(int j = 0; j < n; j++) {
if(list.get(j)[1] != 0) {
bw.write(list.get(j)[0] + " ");
list.get(j)[1] = list.get(j)[1] - 1;
}
}
}
bw.flush();
bw.close();
}
}
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v1.4.16