binarysearch的问题（使用新值计算first，last，mid）
以下代码属于二进制搜索算法。用户在textbox1中输入数字，并在textbox2中输入他想要使用binarysearch查找的数字。
现在我有一个问题，我希望当mid，first，last的值再次改变它时会开始function.i意味着例如：when last = mid-1;函数再次开始并用last的新值计算（我在代码中注释了解更多解释）
谢谢
private void button1_Click(object sender, EventArgs e)
{
string strsearchnums = textBox2.Text;
int result = binarysearch(strsearchnums);
textBox14.Text = result.ToString();
}
public int binarysearch(string strsearchnum)
{
string[] source = textBox1.Text.Split(',');
int[] nums = new int[source.Length];
for (int i = 0; i < source.Length; i++)
{
nums[i] = Convert.ToInt32(source[i]);
}
int searchnum = Convert.ToInt32(strsearchnum);
int first = nums.First();
int last = nums.Last();
while (1 <= nums.Length - 1)
{
int mid = (int)Math.Floor(nums.Length / 2.0) - 1;
if (nums[0]> nums[nums.Length-1])
{
break;
}
if (searchnum < nums[mid])
{
last = mid - 1;
binarysearch(strsearchnum); ///i thought i should do like this but this isnt correct it becomes stackoverflow
}
if (searchnum > nums[mid])
{
first = mid + 1;
binarysearch(strsearchnum); ///i thought i should do like this but this isnt correct it becomes stackoverflow
}
if (searchnum == nums[mid])
{
return nums[mid];
}
}
return -1;
}
没有找到相关结果
已邀请:
4 个回复
驮帽俺篮号
1- Splitt the string with ',' and store in the int[] array. string[] strArray = textBox1.Text.split(new string[]{","}, StringSplitOptions.RemoveEmptyEntries); List<int> lstInts = new List<int>(); foreach(string str in strArray) { int j; int k=0; if(int.TryParse(str,out j)) { lstInts.Add(j); } } int[] bsArray = lstInts.ToArray(); 2- Now Sort the Array. Array.Sort(bsArray); 3- Now use Array.Binaryearch() , if you wanna use framework implementation which is optimized also Array.BinarySearch(bsArray, valueToBeSearched) if you don't wanna use Framework implementation than follow below algorithm public int DoBinarySearchNoNRecursively(int[] array, int value) { int high = array.Length - 1; int low = 0; while (low < high) { int mid = low + (high - low) / 2; if (value == array[mid]) return mid; else if (value > array[mid]) low = mid + 1; else if (value < array[mid]) high = mid; } return -1; }死搭胯
的值 - 所以你总是得到一个Stackoverflow异常，因为它是无限递归。通常，对于递归二进制搜索，您希望binarySearch方法传递您要查找的数字，最小值和最大值，并根据二进制搜索算法修改最小值和最大值。方法签名应该是这样的int binarySearch(int min, int max, int num) { }鞋扣蚊冈借
public int binarysearch(int searchnum) { string[] source = textBox1.Text.Split(','); int[] nums = new int[source.Length]; for (int i = 0; i < source.Length; i++) { nums[i] = Convert.ToInt32(source[i]); } int first = 0; int last = nums.Length - 1; while (1 <= nums.Length) { int mid = (int)Math.Floor((first + last) / 2.0); if (first > last) { break; } if (searchnum < nums[mid]) { last = mid - 1; } if (searchnum > nums[mid]) { first = mid + 1; } if (searchnum == nums[mid]) { return nums[mid]; } } return -1; }淘圃跺枯替
// perform a binary search on the data public int binarysearch(string strsearchnum) { string[] source = textBox1.Text.Split(','); int[] data = new int[source.Length]; for (int i = 0; i < source.Length; i++) { data[i] = Convert.ToInt32(source[i]); } int low = 0 ; // low end of the search area int high = data.length - 1 ; // high end of the search area int middle = ( low + high + 1 ) / 2 ; // middle element int location = -1; // return value; -1 if not found do // loop to search for element { // if the element is found at the middle if ( searchElement == data[ middle ] ) location = middle; // location is the current middle // middle element is too high else if ( searchElement < data[ middle ] ) high = middle - 1 ; // eliminate the higher half else // middle element is too low low = middle + 1 ; // eliminate the lower half middle = ( low + high + 1 ) / 2 ; // recalculate the middle } while ( ( low <= high ) && ( location == -1 ) ); return location; // return location of search key } // end method binarySearch