[算法]各种二叉搜索

1，给定一个有序数组values，求任意一个i使得values[i]等于v,不存在返回-1

int search(int* values,int len,int key)
{
    if(!values || len <=0) return -1;
    int low=0;
    int high=len-1;
    while(low<=high)
    {
        int mid =(low+high)/2;
        if(values[mid]==key) return mid;
        else if(values[mid]>key) high=mid-1;
        else low = mid +1;
    }
    return -1;
}

2,给定一个有序数组values，求最小的i使得values[i]等于v,不存在返回-1

int searchFirst(int * values,int len,int key)
{
    if(!values || len <=0) return -1;
    int low=0;
    int high=len-1;
    while(low<=high)
    {
        int mid =(low+high)/2;
        if(values[mid]==key)
        {
            if(mid==0) return mid;
            else if(values[mid-1]<key) return mid;
            else high=mid-1;
        }
        else if (values[mid]>key) high=mid-1;
        else low=mid+1;
    }
    return -1;
}

3，给定一个有序数组values，求最大的i使得values[i]等于v,不存在返回-1

int searchLast(int* values,int len,int key)
{
    if(!values || len <=0) return -1;
        int low=0;
        int high=len-1;
        while(low<=high)
        {
            int mid =(low+high)/2;
            if(values[mid]==key)
            {
                if(mid==len-1) return mid;
                else if(values[mid+1]>key) return mid;
                else low=mid+1;
            }
            else if (values[mid]>key) high=mid-1;
            else low=mid+1;
        }
    return -1;
}

4，给定一个有序数组values，求最大的i使得values[i]小于v,不存在返回-1

int searchLargestSmallThan(int* values,int len,int key)
{
    if(!values || len <=0) return -1;

    int low=0,high=len-1;
    while(low <= high){
        int mid = (low+high)/2;
        if(values[mid]>=key) high=mid-1;
        else{
            if(mid<len-1 && values[mid+1]>=key) return mid;
            else
                low=mid+1;
        }
    }
    return -1;
}

4，给定一个有序数组values，求最小的i使得values[i]大于v,不存在返回-1

int searchSmallestLargeThan(int* values, int len,int key)
{
    if(!values || len <=0) return -1;
    int low=0,high=len-1;
    while(low <= high){
        int mid = (low+high)/2;
        if(values[mid]<=key) low=mid+1;
        else{
            if(mid>0 && values[mid-1]<=key) return mid;
            else
                high=mid-1;
        }
    }
    return -1;
}