Why am I getting WA? (Right Triangle)

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1

I was solving the Right Triangle problem (https://www.codechef.com/problems/RIGHTTRI)
and I coded the following solution using a bit of trigonometry:-

#include <bits/stdc++.h>
using namespace std;

int main()
{
    long long t;
    cin >> t;

    while(t--)
    {
        long double h, s;
        cin >> h >> s;
        long double val = 4*s/pow(h,2);
        if(!(val > 0 && val < 1))
        {
            cout << -1;
        }
        else
        {
            long double a,b,c;
            long double theta = (asin(val)/2);
            a = h*cos(theta);
            b = h*sin(theta);
            c = h;
            cout << fixed << setprecision(6) << min(a,b) << " " << max(a,b) << " " << c;
        }
        cout << "\n";
    }
    return 0;
}

I am getting exactly the same output as given in the problem:-

3.000000 4.000000 5.000000
-1
-1
285168.817674 546189.769984 616153.000000

But on submitting the solution I am getting WA. What is wrong? Please help.

2

@everule1 It would be great if you could help me with this one.

3

Inaccuracy in floating point calculation
Replace this

if(!(val > 0 && val < 1))
        {
            cout << -1;
        }

by

if(4*s>h*h)
        {
            cout << -1;
        }

standard c++ trigonometric functions use floats, which are inaccurate.

2 Likes
4

@everule1 Thank you so much ! :smiley:

5

I have a doubt, is there any way by which we can increase accuracy of the trigonometric functions?

6

Define your own trigonometric function, and use at least 7-8 terms of the taylor series. I don’t know about any accurate inbuilt trigonometric functions and couldn’t find it on the internet.

2 Likes
7

Thanks for the fast response ! :smiley:

8

I can’t really leave my house so…

1 Like