Pretty weird problem. The failing tests, to be more specific. Similarly to jasonaboatman's situation, my solution works well for the original Project Euler problem#228. But for this (HackerRank) version, my solution solves only the first three (open) tests. Is there any chance that the remaining tests are wrong?

You can graph your results in wolfram alpha if you want a quick way to visualize your progress (only works for 10 vertices, so only good for basics)

polygon with vertices [(2.00,0.00),(1.00,1.00),(-0.50,1.87),(-1.50,0.87),(-1.50,-0.87),(-0.50,-1.87),(1.00,-1.00)]

displays as: https://www.wolframalpha.com/input/?i=polygon+with+vertices+%5B(2.00,0.00),(1.00,1.00),(-0.50,1.87),(-1.50,0.87),(-1.50,-0.87),(-0.50,-1.87),(1.00,-1.00)%5D

Python pseudocode:

link = 'https://www.wolframalpha.com/input/?i=polygon+with+vertices+'+str(vertices).replace(" ", "")

where vertices are an array of objects that have:

    def __repr__(self):
        x = '{:6.2f}'.format(self.x)
        y = '{:6.2f}'.format(self.y)
        return "("+x+","+y+")"

Like others, failing all but first 3 cases. I even tried to validate my process geometrically - seems right (but obviously issues exist).

Any chance to get just one more semi-extreme test case to look at? Or, is not having those available part of the fun?

Greetings Khalid,

Could you please upload an explaination with different number of quries to help better explain the problem.

Regards.

result = (summation from L to R) - (R - L); = ((R(R + 1)/ 2) - ((L - 1)(L)/2)) - (R - L); = (R(R-1)/2) - (L(L - 1)/ 2) + L; = L + ((R(R-1) - L(L-1))/2);

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int main()
{
    int q;
    unsigned long L, R;
    unsigned long result = 0;
    scanf("%d", &q);
    
    while(q > 0)
    {
        scanf("%ld %ld", &L, &R);
        if(L >= 3 && R > 3 && L < R)
            result = L + (((R * (R - 1)) - (L * (L - 1))) / 2);
        printf("%ld\n", result);
        q--;
    }
    return 0;
}

Only the testcase 0, 1, 2 are passing.. All other testcases are failing.. Please let us know the usecases..