[数据结构与算法]数据结构学习第二十五课(二分查找)

二分查找:

在有序序列中查找,每次忽略一半

1 源文件

/*
测试用值:
15 20 32 46 57 77 89 133 456 966
*/

#include<stdio.h>


int halfFind(int* arr, int len, int data);
int main()
{
	int arr[] = { 15 ,20 ,32 ,46 ,57 ,77 ,89 ,133 ,456 ,966 };
	int n;
	int r;
	while (1)
	{
		printf("请输入要查找的值:");
		scanf_s("%d", &n);
		if (66666 == n)
			break;
		r = halfFind(arr, 10, n);
		if (r >= 0)
		{
			printf("找到了%d,%d;\n", r, n);
		}
		else
		{
			printf("没找到\n");
		}
	}
	

	return 0;
}

int halfFind(int* arr, int len, int data)
{
	int right = len - 1;
	int left = 0;
	int mid = (right + left) / 2;

	while (1)
	{
		if (arr[mid] == data)
			return mid;
		else if (arr[mid] < data)
		{
			left = mid + 1;
		}
		else
		{
			right = mid - 1;
		}
		mid = (right + left) / 2;
		if (left > right)break;
	}
	return -1;
}