Color of the cars [closed] - algorithm

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Could you give me a hint on how to solve this problem?
How can I find out whether most cars have the same color if the only function I can use is to check whether two cars have the same color?

Answer 1

With equality, you can first build equivalence classes and then count the largest one.

Answer 2

You can create a "list" where the color of the car is the key value and it counts how many cars of that color you have and stores a car of that color.
It goes something like this:
you will have a struct of with this fields:
struct color
car *car_with_color = NULL
int count = 0
so you go to the first car store it's color and add 1:
color[1].car_with_color=&cars[1];
color[1].count=1;
then for the next car you do:
if (cars[2].color == color[1].car_with_color->color)
color[1].count++;
else
color[2].car_with_color=&cars[2];
color[2].count=1;
and so on:
for (i=1;i<=NUM_OF_CARS;i++){
j=1;
while (color[j].car_with_color != NULL){
if (cars[i].color == color[j].car_with_color->color){
color[i].count++;
break;
}else
j++;
}
if (color[j].car_with_color == NULL){
color[j].car_with_color=&cars[i];
color[j].count=1;
}
}
it's written in a C like pseudo-code.