bsearch—二分查找

【非对称】

1----------------------------------------------------------------------------------

int *bsearch(int *array, int len, int x){

    int *low = array;

    int *high = low + len;

    while(low < high){

       int *mid = low + ((high - low) >> 1);

       if(x < *mid){

           high = mid;

       }else if(x > *mid){

           low = mid + 1;

       }else{

           return mid;

       }

    }

    return NULL;

}

2----------------------------------------------------------------------------------

int *bsearch(int *array, int len, int x){

    int low = 0;

    int high = len;

    while(low < high){

        int mid = (low + high)  >> 1;

        if(x < t[mid]){

            high = mid;

        }else if(x > t[mid]){

            low = mid + 1;

        }else{

            return array + mid;

        }

    }

    return NULL;

}

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2[对称]

int *bsearch(int *array, int len, int x){

    if(len == 0)

       return;

    int low = 0;

    int high = n - 1;

    int mid = (low + high) >> 1;

    if(x < t[mid]){

       high = mid - 1;

    }else if(x > t[mid]{

       low = mid + 1;

    }else{

       return array + mid;

    }

    return NULL;

}