英文:
Indenting an output with recursion
问题
public class Practice1 {
/**
* 每次递归打印出两行文本，并在每次递归时增加缩进（示例在javadoc下方）。我知道使用 `(numCalls + 1)` 可以使缩进逐渐增加，但我不确定如何将所有部分组合起来以实现题目要求的功能。
*
* 对于每次递归调用，应该打印出2行文本，指示调用编号
* （一个大于等于1且小于等于numCalls的值，如下所示）。
* 每层递归应该通过在输入行前添加r个空格来表示缩进。
* 例如，如果numCalls为3，则方法应打印：
* call 1
* call 2
* call 3
* back 3
* back 2
* back 1
*
* @param r 方法调用的层级
* @param numCalls 所需的层级数
*/
public static void stairSteps(int r, int numCalls) {
if (r == 0) {
System.out.println("Done");
} else {
System.out.println("call " + r);
System.out.println("back " + r);
r--;
numCalls++;
stairSteps(r, numCalls);
}
}
}
英文:
I am trying to use recursion to print out two lines of text each and with an indent every time there's recursion (example in javadoc below). I know using (numCalls + 1) will allow it to increase the indent each time but I'm not sure how to actually put it together so does what it is asking for.
public class Practice1 {
/**
* Prints 2 lines of text for each recursive call, indicating call number
* (a value >= 1, and <= value of numCalls, as illustrated below. Each
* level of recursion should be indicated by indenting the input line by
* r spaces. For example, if numCalls is 3, the method should print:
* call 1
* call 2
* call 3
* back 3
* back 2
* back 1
* @param r the level of method calls
* @param numCalls the number of intended levels
*/
public static void stairSteps(int r, int numCalls) {
if (r == 0) {
System.out.println("Done");
} else {
System.out.println("call " + r);
System.out.println("back " + r);
r--;
numCalls++;
stairSteps(r, numCalls);
}
}
答案1
得分: 1
public static void stairSteps(int totalLevels, int indent) {
stairSteps(1, totalLevels, indent);
System.out.println("Done");
}
private static void stairSteps(int level, int totalLevels, int indent) {
if (level <= totalLevels) {
int offs = indent * (level - 1);
System.out.println(" ".repeat(offs) + "call " + level);
stairSteps(level + 1, totalLevels, indent);
System.out.println(" ".repeat(offs) + "back " + level);
}
}
**输出:**
stairSteps(3, 2);
call 1
call 2
call 3
back 3
back 2
back 1
Done
英文:
public static void stairSteps(int totalLevels, int indent) {
stairSteps(1, totalLevels, indent);
System.out.println("Done");
}
private static void stairSteps(int level, int totalLevels, int indent) {
if (level <= totalLevels) {
int offs = indent * (level - 1);
System.out.println(" ".repeat(offs) + "call " + level);
stairSteps(level + 1, totalLevels, indent);
System.out.println(" ".repeat(offs) + "back " + level);
}
}
Output:
stairSteps(3, 2);
call 1
call 2
call 3
back 3
back 2
back 1
Done
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