英文:
Is there a way to convert this iterative function that takes a Collection of Integer objects and adds these elements, into a recursive one?
问题
最初，我们被鼓励使用递归来解决这个问题，但到目前为止，我只能想到一个迭代的方法。
import java.util.*;public class Problem1 {static Integer add(Collection integers) {Integer sum = 0;Iterator iterator = integers.iterator();while (iterator.hasNext()) {sum = sum + (Integer) iterator.next();}return sum;}}
英文:
Originally, we were encouraged to solve the problem with recursion, but so far I can only think of an interative one.
import java.util.*;public class Problem1 {static Integer add(Collection integers) {Integer sum = 0;Iterator iterator = integers.iterator();while (iterator.hasNext()) {sum = sum + (Integer) iterator.next();}return sum;}}
答案1
得分: 0
用一种方法是在递归过程中使用迭代器遍历然后移除元素。
public class Problem1 {static Integer add(Collection integers) {Integer sum = 0;Iterator it = integers.iterator();if (!it.hasNext()) {return 0;}Integer number = (Integer)it.next();it.remove();sum += number + add(integers);return sum;}}
英文:
One way to do it is to use then remove the elements as you recurse through using an iterator.
public class Problem1 {static Integer add(Collection integers) {Integer sum = 0;Iterator it = integers.iterator();if (!it.hasNext()) {return 0;}Integer number = (Integer)it.next();it.remove();sum += number + add(integers);return sum;}}
答案2
得分: 0
尝试这个。
static Integer add(Iterator it) {if (!it.hasNext())return 0;elsereturn (Integer)it.next() + add(it);}static Integer add(Collection integers) {return add(integers.iterator());}
和
Collection integers = List.of(1, 2, 3, 4);System.out.println(add(integers));
输出
10
英文:
Try this.
static Integer add(Iterator it) {if (!it.hasNext())return 0;elsereturn (Integer)it.next() + add(it);}static Integer add(Collection integers) {return add(integers.iterator());}
and
Collection integers = List.of(1, 2, 3, 4);System.out.println(add(integers));
output
10
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