代码

int binary_search(const unsigned *line, int ub, unsigned value){
register int down = 0,up=ub - 1;
register int estimate = 0;
    while(1){
        estimate = down + 
        (unsigned long long)(up - down) *
        (value - line[down]) / (line[up] - line[down]);
        if( estimate == down ) ++ estimate ;
        if( estimate == up   ) -- estimate ;
        if( line[estimate] == value )return estimate;
        ( line[estimate] < value ? down : up ) = estimate;
    }
    return 0;
}

评测结果