Discussion about PRIMEDST

help
,
1 
#include <bits/stdc++.h>
using namespace std;
int prime(int subject){
  if(subject == 1){
    return 0;
  }
  if(subject == 2){
    return 1;
  }
  if(subject == 3){
    return 1;
  }
  if(subject == 4){
    return 0;
  }
  if(subject == 5){
    return 1;
  }
  for(int i = 2; i <= (subject/2 + 1); i++){
    if(subject % i == 0){
      return 0;
    }
  }
  return 1;
}
int factorial(int subject){
  if(subject == 0){
    return 1;
  }
  if(subject == 1){
    return 1;
  }
  int answer = 1;;
  for(int i = 1; i <= subject; i++){
    answer = answer * i;
  }
  return answer;
}
int main(){
  int n;
  cin >> n;
  int matrix[n + 1][n + 1];
  for(int i = 0; i <= n; i++){
    for(int j = 0; j <= n; j++){
      matrix[i][j] = 191919;
    }
  }
  for(int i = 1; i <= n; i++){
    matrix[i][i] = 0;
  }
  for(int i = 1; i < n; i++){
    int firstvar;
    int secondvar;
    cin >> firstvar;
    cin >> secondvar;
    matrix[firstvar][secondvar] = 1;
    matrix[secondvar][firstvar] = 1;
  }
  float totalprime = 0;
  for(int i = 1; i <= n; i++){
    for(int j = 1; j <= n; j++){
      if(i != j){
        for(int k = 1; k <= n; k++){
          if(k != i){
            if(k != j){
              matrix[i][j] = min((matrix[i][k] + matrix[k][j]), matrix[i][j]);
              matrix[j][i] = matrix[i][j];
            }
          }
        }
      }
    }
  }
  for(int i = 1; i <= n; i++){
    for(int j = 1; j <= n; j++){
      if(j != i){
        if(prime(matrix[i][j]) == 1){
          totalprime = totalprime + 1;
        }
      }
    }
  }
  totalprime = totalprime/2;
  float answer1 = factorial(n)/(2 * factorial(n - 2));
  float answer_finale = totalprime/answer1;
  cout << answer_finale;
  return 0;
}

My Code is getting SIGFPE error. Please help me find answer.

2

int statement wrong prime(int subject)[

clrscr()
}

3

SIGFPE is the easiest runtime error to debug - it is a floating point error. It is virtually always caused by a division by 0, so check any divisions or modulo operations in your code carefully.

1 Like
4

Hi, but I have checked all the divisions and made factorial(0) = 1 and factorial (1) = 1 and then we can do the factorials from 2 onwards with the help of the function… So is there any other areas that I should check? Thank you for the help.

5

Can you share link to your submission?

6

Here’s the log when your code is compiled using Debug flags and executed.

Compiling RTE.cpp using Debug Flags
Now Running RTE.cpp in Debug Mode
RTE.cpp:35:12: runtime error: signed integer overflow: 479001600 * 13 cannot be represented in type 'int'
RTE.cpp:84:31: runtime error: division by zero
AddressSanitizer:DEADLYSIGNAL
=================================================================
==16856==ERROR: AddressSanitizer: FPE on unknown address 0x55be44d7e162 (pc 0x55be44d7e162 bp 0x7fff2c0f1d10 sp 0x7fff2c0d6c80 T0)
    #0 0x55be44d7e161 in main /home/suman/Temp/RTE.cpp:84
    #1 0x7fa054a580b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #2 0x55be44d7c40d in _start (/home/suman/Temp/exe+0x540d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: FPE /home/suman/Temp/RTE.cpp:84 in main
==16856==ABORTING
suman@Skynet:~/Temp$

If you don’t get it, check the line 84 in your code.

float answer1 = factorial(n)/(2 * factorial(n - 2));

Your code crashes there due to a Floating-point error.

2 Likes
7

Hi, I corrected the error., but I am getting wrong answer now… Can anybody give me the test cases for this problem. PRIMEDST

8

https://www.codechef.com/viewsolution/56744695
This is the link.
Thank you for the help in advance.