OJ Board

Posted: **Sat Apr 08, 2006 8:04 pm**

the c++ compiler cant compile the program below, it just responds as "Recieved", and sometimes compile error. whats the problem?

#define NDEBUG

#include <cstdio>
#include <cassert>
#include <iostream>
#include <complex>
#include <cmath>
using namespace std;

typedef complex<int> point, vect;
typedef long long int64;

int64 Cross(const vect &u, const vect &v)
{
return (conj(u) * v).imag();
}

bool onseg(const point &P, const point seg[2])
{
return (P.real() >= min(seg[0].real(), seg[1].real()) &&
P.real() <= max(seg[0].real(), seg[1].real()) &&
P.imag() >= min(seg[0].imag(), seg[1].imag()) &&
P.imag() <= max(seg[0].imag(), seg[1].imag()));
}

int sgnll(int64 x)
{
if (x > 0)
return 1;
if (x < 0)
return -1;
return 0;
}

bool intersect(const point seg[2][2])
{
bool nepi = true; /* non endpoint intersection */
for (int i = 0; i < 2; ++i)
{
int64 dir[2];
for (int j = 0; j < 2; ++j)
{
dir[j] = Cross(seg[!i][0] - seg[j], seg[!i][1] - seg[j]);
if (dir[j] == 0 && onseg(seg[j], seg[!i]))
return true;
}
int s[2] = {sgnll(dir[0]), sgnll(dir[1])};
nepi &= (s[0] == 1 && s[1] == -1) || (s[0] == -1 && s[1] == 1);
}
return nepi; /* no epi's left to concern about */
}

point getp()
{
int x, y;
scanf("%d %d", &x, &y);
return point(x, y);
}

int main()
{
int ntc;
scanf("%d", &ntc);
for (int tc = 0; tc < ntc; ++tc)
{
point P[2] = {getp(), getp()}, R[2][2] = {{getp(), getp()}};

for (int k = 0; k < 2; ++k)
R[1][k] = point(R[0][k].real(), R[0][!k].imag());

/* for (int i = 0; i < 2; ++i)
for (int j = 0; j < 2; ++j)
cerr << "R[" << i << "][" << j << "]: " << R[j] << endl;*/

bool res = false;
for (int k = 0; k < 2; ++k)
{
res |= onseg(P[k], R[0]);
const point seg[2][2] = {{P[0], P[1]}, {R[k][0], R[k][1]}};
res |= intersect(seg);
}

if (res)
printf("T\n");
else
printf("F\n");
}

return 0;
}

Posted: **Sun Apr 09, 2006 5:36 am**

What compiler are you using?

I got the following errors when I compiled with g++ 2.95.3:

Code: Select all

testing.cpp: In function `bool onseg(const point &, const complex<int> *)':
testing.cpp:20: implicit declaration of function `int min(...)'
testing.cpp:21: implicit declaration of function `int max(...)'
testing.cpp: In function `int main()':
testing.cpp:79: conversion from `const complex<int>[2]' to non-scalar type `complex<int>' requested
testing.cpp:79: conversion from `const complex<int>[2]' to non-scalar type `complex<int>' requested

min and max are defined in the algorithm library. You have to include all the libraries you used in your program explicitly as the compiler in this OJ does not do it for you.

Also this line of code is causing some weird compile error:

Code: Select all

const point seg[2][2] = {{P[0], P[1]}, {R[k][0], R[k][1]}};

Remove the const qualifier to correct this error, although this does not make any sense since your intersection function takes in a const complex<int>. I am not sure why this is happening. Can any C/C++ expert explain?

Posted: **Sun Apr 09, 2006 9:21 am**

thanks. it compiled.
I use g++ 3.3.3, But I didnt get any on those errors on my compiler.
How does the online-judge compiler detect all headers needed?
Can I compile that way on my PC?

Posted: **Mon Apr 10, 2006 3:27 am**

OJ doesn't detect what headers to use, it just includes the headers you include explicitely.

As this problem is solved, and I don't knkow the exact compile command (i should dig into the source to get that> too troublesome) I close this topic.

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c++ compiler problems

c++ compiler problems