折半查找

int Search_Bin(unsort[], int K) {
    int low=1, high=ST.length;
    int mid;
    while (low<=high) {
        mid=(low+high)/2; //mid=low+ (key-a[low])/(a[high]-a[low]) *(high-low)
        if (K<unsort[mid])
            high=mid-1;     //在左区间继续查找
        else if (K>unsort[mid])
            low=mid+1;  //在右区间继续查找
        else  return mid;   //查找成功的出口
   } 
   return 0;      //查找失败的出口
}