Your text to link here... Hi, I was doing this problem on SPOJ. It basically asks us to find total number of distinct slopes among n different points. Pretty easy( n <= 200).
So I did it using two approaches. First, I run two loops calculating all the slopes (the points are integers,and I took care and took input as doubles) and insert them in a set < double > taking care of case when dx =0 (slope = dy/dx). This approach got WA.
In second, I do the same thing but I push the slopes in a vector and then sort the vector and take care of duplicates. This Got AC.
Your text to link here...- Approach 1.-WA
Your text to link here...- Approach 2.- AC.
Can someone explain me the reason for this.
Thank You.
One does not simply check equality in doubles by
==, !=. Identical doubles can differ in the last few significant digits, so you should check if their absolute difference is small enough.Oh !. But regardless, it worked in the second approach. I don't know why using a set gave WA and vector AC. Could you be more explicit. Thank You.
My guess is luck or that equality comparison with doubles messes up sets somehow.