使用递归打印从[0,0,0,0]到[9,9,9,9]I的数组
使用递归打印从[0,0,0,0]到[9,9,9,9]I的数组
提问于 2017-07-24 01:21:22
我只想使用递归打印一个从0，0，0到9,9,9,9的数组。首先，我编写了如下代码：
public class PrintNumber {
public static void main(String[] args) {
int N = 4;
int[] number = new int[N];
PrintNumber printNumber = new PrintNumber();
printNumber.printNum(number,0);
}
public void printNum(int[] number, int bit) {
if (bit == number.length ) {
System.out.println(Arrays.toString(number));
return;
}
for (int i = 0; i < 10; i++) {
number[bit] = i;
/******** something goes wrong here ********/
printNum(number, ++bit);
/******** something goes wrong here ********/
}
}
}如您所见，代码不是很多，但它不起作用。所以我调试了我的代码，我发现++bit (代码的最后一行)应该写成bit+1。然后，它工作得很好。
但是我真的很困惑，为什么呢？++bit和bit+1都是将位加1，为什么它不适用于++bit，而适用于bit+1？
非常感谢。
回答 1
Stack Overflow用户
发布于 2017-07-24 01:36:36
这是一个可行的解决方案。
import java.util.Arrays;
public class TestTest {
private static int N = 4;
private static int MAX = 10;
public static void main(String[] args) {
int[] number = new int[N];
TestTest printNumber = new TestTest();
printNumber.printNum(number,0);
}
public void printNum(int[] number, int bit) {
System.out.println(Arrays.toString(number));
if (bit == MAX ) {
return;
}
for (int i = 0; i < N; i++) {
number[i] = bit;
}
printNum(number, ++bit);
}
}有几个问题：
- 您混合了循环和recurection.
- Wrong数组大小
- 数组值错误
- 错误打印if-
- 错误函数退出。
此代码产生堆栈溢出异常。但它适用于N = 3
public class TestTest {
private static int N = 3;
private static int MAX = 10;
public static void main(String[] args) {
int[] number = new int[N];
TestTest printNumber = new TestTest();
printNumber.printNum(number);
}
public void printNum(int[] number) {
System.out.println(Arrays.toString(number));
// if (bit == MAX) {
// return;
// }
boolean exit = true;
for (int i = 0; i < N; i++) {
if (number[i] != MAX - 1) {
exit = false;
}
}
if (exit) {
return;
}
number[N - 1]++;
for (int i = N - 1; i >= 0; i--) {
if (number[i] == MAX) {
if (i > 0) {
number[i - 1]++;
number[i] = 0;
}
}
}
printNum(number);
}
}循环解决方案：
public class TestTest {
private static int N = 4;
private static int MAX = 10;
public static void main(String[] args) {
int[] number = new int[N];
TestTest printNumber = new TestTest();
// printNumber.printNum(number);
printNumber.printNumLoop(number);
}
private void printNumLoop(int[] number) {
while(true) {
System.out.println(Arrays.toString(number));
number[N - 1]++;
for (int i = N - 1; i >= 0; i--) {
if (number[i] == MAX) {
if (i > 0) {
number[i - 1]++;
number[i] = 0;
}
}
}
boolean exit = true;
for (int i = 0; i < N; i++) {
if (number[i] != MAX - 1) {
exit = false;
}
}
if (exit) {
System.out.println(Arrays.toString(number));
break;
}
}
}
public void printNum(int[] number) {
// if (bit == MAX) {
// return;
// }
boolean exit = true;
for (int i = 0; i < N; i++) {
if (number[i] != MAX - 1) {
exit = false;
}
}
if (exit) {
return;
}
number[N - 1]++;
for (int i = N - 1; i >= 0; i--) {
if (number[i] == MAX) {
if (i > 0) {
number[i - 1]++;
number[i] = 0;
}
}
}
printNum(number);
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/45267882
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