二分法查找

    二分法查找需要序列有序

#include<stdio.h>
#include<assert.h>

int binary_search(int *array,int n,int e)
{
    assert(array&&n>0);
    int low=0,high=n-1,mid;
    
    while(low<=high)
    {
        mid=(low+high)/2;
        if(array[mid]==e)
            return mid;
        if(array[mid]>e)
            high=mid-1;
        else
            low=mid+1;
    }
    return -1;
}

int main()
{
    int a[100];
    int i;
    int e;
    
    for(i=0;i<100;i++)
        a[i]=i;
    
    scanf("%d",&e);
    int index=binary_search(a,100,e);
    if(-1==index)
        printf("Can not find %d\n",e);
    else
        printf("%d index=%d\n",e,index);
    
    getchar();
    getchar();
    return 0;
}