使用递归在数组中查找值

Question

我试图用特定的方法在数组中找到一个值.

public void findElement(int valueToFind)
{
    FindElementInArray(valueToFind, 0, _array.Length - 1);
}

public void FindElementInArray(int value, int lb, int rb)
    {          
        int currIndex = (rb - lb) / 2;
        if (_array[currIndex] == value)
        {
            //Value found
            Console.WriteLine("Value found");
            return;
        }

        //If found value is smaller than searched value
        else if (_array[currIndex] < value)
        {
            FindElementInArray(value, currIndex+1, rb);
        }

        //If found value is bigger than searched value
        else
        {
            FindElementInArray(value, lb, currIndex - 1);
        }   

所以我搜索数组的中间,如果值大于我们寻找的值,我们搜索左半部分的中间,依此类推......

但即使它们在阵列中,它也找不到一些值.有人能看到错误吗？

Answer 1

你使用索引错了.

int currIndex = (rb - lb) / 2;

你需要获得rb和lb的中间点,这将是:

int currIndex = lb + (rb - lb) / 2;
// or
// int currIndex = (lb + rb) / 2;

如果值不存在,您还需要以某种方式退出递归,因为当前它将继续并导致堆栈溢出.你可以通过检查以确保lb和rb不同,例如:

if (_array[currIndex] == value)
{
    //Value found
    Console.WriteLine("Value found");
    return;
}
else if (lb != rb)
{
    //If found value is smaller than searched value
    else if (_array[currIndex] < value)
    {
        FindElementInArray(value, currIndex+1, rb);
    }

    //If found value is bigger than searched value
    else
    {
        FindElementInArray(value, lb, currIndex - 1);
    }   
}