【算法】【查找】二分法 Bisection

#include<stdio.h>

int main(){
    int a[]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
    int l=sizeof(a)/4;        //长度 
    int x=10;                //要查找到的值 
    
    int Bisection(int x,int* a,int l); 
    Bisection(x,a,l); 
    
    return 0;
} 

int Bisection(int x,int* a,int l){
    int address;    //查找的数的位置 
    //先考虑两端的位置 
    if(x==a[l-1]){
        address=l-1;
        printf("%d
",address);
        return address;
    }else if(x==a[0]){
        address=0;
        printf("%d
",address);
        return address;
    }
    //如果不在两端 
    address=l/2;
    l=l/2;
    while(true){
        if(x==a[address]){
            printf("%d
",address);
            break;
        }else if(x>a[address]){
            l=l/2;
            address=address+l;
        }else if(x<a[address]){
            l=l/2;
            address=address-l;
        }
        if(l==0){ 
            //如果l=0了表示找不到 
            printf("not found");
            break; 
        } 
    }     
    return address;
}