折半查找

来源：互联网发布：js 判断 arguments 编辑：程序博客网时间：2024/05/16 07:37

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
int binsearch(int a[], int n, int x)
{
   int low, mid, high;
   low = 0;
   high = n - 1;
   while (low <= high)
   {
       mid = (low + high) / 2;
       if (x<a[mid])
       {
           high=mid - 1;
       }
       else if (x>a[mid])
       {
           low = mid + 1;
       }
       else
       {
           return mid;
       }
   }
   return -1;
}
int main()
{
   int x, result;
   int arr[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };//要查找的数据已经排好序
   printf("请输入你要查找的数：");
   scanf("%d", &x);
   result = binsearch(arr, 10, x);
   if (result < 0)
   {
       printf("没有找到\n");
   }
   else
   {
       printf("在arr[%d]找到%d\n", result, x);
   }

   system("pause");
   return 0;
}

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
int BinSearch(int a[], int x, int left, int right)
{
   int middle;
   if (left<=right)
   {
       middle = (left+right) / 2;
       if (x < a[middle])
       {
           right = middle - 1;
       }
       else if (x>a[middle])
       {
           left = middle + 1;
       }
       else
       {
           return middle;
       }
       return BinSearch(a, x, left, right);
   }
   return -1;
}
int main()
{
   int num, result;
   int arr[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };//要查找的数据已经排好序
   printf("请输入你要查找的数：");
   scanf("%d", &num);
   result = BinSearch(arr, num, 0, 9);
   if (result < 0)
   {
       printf("没有找到\n");
   }
   else
   {
       printf("在arr[%d]找到%d\n", result, num);
   }

   system("pause");
   return 0;
}

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