递归求和数组中的整数 [英] recursively sum the integers in an array
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问题描述
我有一个程序,我正在尝试为类编写一个程序,该程序使用递归返回数组中所有整数的总和.到目前为止,这是我的程序:
I have a program that I'm trying to make for class that returns the sum of all the integers in an array using recursion. Here is my program thus far:
public class SumOfArray {
private int[] a;
private int n;
private int result;
public int sumOfArray(int[] a) {
this.a = a;
n = a.length;
if (n == 0) // base case
result = 0;
else
result = a[n] + sumOfArray(a[n-1]);
return result;
} // End SumOfArray method
} // End SumOfArray Class
但是我收到了三个相关的错误,我相信,但我不明白为什么它会找到一种空值:
But I'm getting three error which are all related, I believe, but I can't figure out why it is finding a type of null:
SumOfArray.java:25: sumOfArray(int[]) in SumOfArray cannot be applied to (int)
result = a[n] + sumOfArray(a[n-1]);
^
SumOfArray.java:25: operator + cannot be applied to int,sumOfArray
result = a[n] + sumOfArray(a[n-1]);
^
SumOfArray.java:25: incompatible types
found : <nulltype>
required: int
result = a[n] + sumOfArray(a[n-1]);
^
3 errors
推荐答案
解决方案比看起来更简单,试试这个(假设一个非零长度的数组):
The solution is simpler than it looks, try this (assuming an array with non-zero length):
public int sumOfArray(int[] a, int n) {
if (n == 0)
return a[n];
else
return a[n] + sumOfArray(a, n-1);
}
这样称呼它:
int[] a = { 1, 2, 3, 4, 5 };
int sum = sumOfArray(a, a.length-1);
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