[数据结构与算法] : 二分查找

#include <stdio.h>

#define NotFound -1;
typedef int ElementType;

int BinarySearch( const ElementType A[], ElementType X, int N )
{
    int Low, Mid, High;

    Low = 0; High = N-1;
    while( Low <= High ) // 注意终止条件
    {
        Mid = (Low + High) / 2;
        if( A[Mid] < X )
            Low = Mid + 1;
        else if( A[Mid] > X )
            High = Mid - 1;
        else
            return Mid;
    }
    return NotFound;
}

int main()
{
    int arr[10] = {1, 2, 3, 5, 6, 7, 9, 10, 12, 15};
    int sizeofA = sizeof(arr) / sizeof(arr[0]);
    printf("BinarySearch returns %d
", BinarySearch(arr, 9, sizeofA));
    return 0;
}