即使不再满足条件，while循环也会继续

Question

public class SumOfTwoNum {
    public int[] twoSum(int[] numbers, int target) {
        int med = numbers.length/2;
        if (numbers[med] > target) {
            twoSum(Arrays.copyOfRange(numbers,0,med), target);
        }
        int remainNum;
        int index1 = -1;
        int index2 = -1;
        while (index1 == -1 && index2 == -1) {
            remainNum = target-numbers[med];
            if (remainNum > numbers[med]) {
                index2 = Arrays.binarySearch(numbers,med,numbers.length,remainNum);
                index1 = med;
            } else {
                index1 = Arrays.binarySearch(numbers,0,med,remainNum);
                index2 = med;
            }
            //here I get index1=0 and index2=1, but the loop doesn't stop
            med --;

        }
        return new int[] {index1, index2};
    }

    public static void main(String[] args) {
        SumOfTwoNum s = new SumOfTwoNum();
        System.out.println(Arrays.toString(s.twoSum(new int[] {2,7,11,15},9)));
        //what I hope to get here is {0,1}, but it returns {-1,2}
    }
}

我想得到两个数字的索引，这两个数字加起来就是目标，但是当它进入循环时，即使 index1 和 index2 都不是-1，它仍然会继续循环

Answer 1

问题是在递归调用之后，你的 function 没有返回，所以循环执行了两次。 这就是为什么即使条件变为假，循环似乎也在执行的原因。

您需要返回递归调用的结果。

if (numbers[med] > target) {
     return twoSum(Arrays.copyOfRange(numbers,0,med), target);
}