int Bi_Search(int a[],int n,int b)//

{//返回等于b的第一个

if(n==0)

return -1;

int low = 0;

int high = n-1;

int last = -1;//用last记录上一次满足条件的下标

while (low<=high)

{

int mid = low +(high-low)/2;

if (a[mid]==b)

{

last = mid;

high = mid -1;

}

else if(a[mid]>b)

high = mid -1;

else

low = mid +1;

}

return last;

}

 

 

 

int Bi_Search1(int a[],int n,int b)//大于b的第一个数

{

if(n<=0)

return -1;

int last = -1;

int low = 0;

int high = n-1;

while (low<=high)

{

int mid = low +(high - low)/2;

if(a[mid]>b)

{

last = mid;

high = mid -1;

}

else if (a[mid]<=b)

{

low =mid +1;

}

}

return last;

}